1 Introduction: Cascade Head SCUBA Fish Surveys

SCUBA fish sampling monitors the density of select benthic fish species, following PISCO modified protocols, at depths between 10-20m. Midwater and canopy fishes are not included in Oregon Marine Reserves monitoring. Fish are counted along a 30 x 2 m belt transects across three target depths, 10, 15 and 20 meters. Species write-ins are allowed for species not specifically identified on PISCO datasheets.

Our SCUBA fish sampling at Cascade Head began in 2014, the year harvest restrictions began. Sampling is conducted in the marine reserve and two comparison areas, Cavalier and Schooner Creek (see methods Appendix for additional information about comparison area selection). We conducted three years of sampling that are included in our analysis and report. Note, successful sampling in Cavalier did not begin until 2017.

Table 1: Cascade Head SCUBA Fish Monitoring Efforts. Sample sizes represent the number of transects per year at each site

Data from SCUBA fish monitoring efforts can be used to explore questions about fish diversity, community composition and density. Questions about diversity and community composition can be used to compare across monitoring tools to understand tool bias or to validate trends seen across tools. This can further help us understand how the fish communities at these sites are similar or different. Data on density enable us to explore changes over time; and whether these changes are similar both inside the reserve and outside in comparison areas. For all data our main focus is exploring trends by site and year.

1.1 Survey Maps

1.1.1 Cascade Head Marine Reserve

Fig. 1: Map of SCUBA transect locations at Cascade Head Marine Reserve

1.1.2 Schooner Creek Comparison Area

Fig. 1: Map of SCUBA transect locations at Schooner Creek Comparison Area

1.1.3 Cavalier Comparison Area

$Fig. 1: Map of SCUBA transect locations at Cavalier Comparison Area$

Fig. 1: Map of SCUBA transect locations at Cavalier Comparison Area

1.2 Research Questions

Diversity

Does species diversity vary by site or year?

Community Composition

Does community composition vary by site or year?
- If yes, what species drive this variation?

Aggregate Abundance

Does aggregate density vary by site or year?

Focal Species Abundance

Does focal species density vary by site or year?
Does focal species size vary by site or year?

2 Takeaways

Here we present a summary of our SCUBA fish monitoring results and our conclusions. Our conclusions are written with an evaluation of our sampling design, knowledge from prior marine reserves monitoring reports, and future directions of marine reserves monitoring in mind.

2.1 SCUBA Fish Results Summary

Fish species diversity is most similar between Cascade Head Marine Reserve and Schooner Creek Comparison Area, but more surveys are needed to evaluate the Cavalier Comparison Area.

Fish species diversity is most similar between the Cascade Head Marine Reserve and Schooner Creek Comparison Area. They have similar numbers of observed species, they also have similar numbers of rare species. Diversity indices are most similar between the Cascade Head Marine Reserve and Schooner Creek Comparison Area. A greater number of transects also occurred at these sites; likely with more success at the Cavalier Comparison Area for fish visibility, we would gain more confidence in understanding the fish community at this comparison area site.

Limited data suggest fish community composition is similar between sites and years.

There was no apparent structuring of fish community by sites or year at the Cascade Head Marine Reserve and its associated comparison areas. Data were limited from the Cavalier Comparison Area, but transect fish community composition was similar to the other sites. Three schooling species drove the majority of transect variation in the fish community composition - Black, Canary, and Yellowtail Rockfish. The difference in community structure between the marine reserve and its comparison area sites is mostly driven by differences in Black Rockfish. Yellowtail and Canary Rockfish were relatively rare among all sites but in one transect at Schooner Creek where there was high abundance of both species.

Aggregate fish density was lower at the Cascade Head Marine Reserve than Schooner Creek Comparison Area, likely driven by differences in schooling species.

There was lower aggregate fish density at the marine reserve than the Schooner Creek Comparison Area. Aggregate density was likely influenced by the most abundant species at each site, which for Schooner Creek included schooling species such as Blue/Deacon, Canary and Yellowtail Rockfish that were not observed in large numbers at the Cascade Head Marine Reserve. Cavalier Comparison Area was not included in this analysis because of limited data.

No yearly trends in aggregate density were detected at any site.

There were no yearly trends in aggregate density at the Cascade Head Marine Reserve or Schooner Creek Comparison Area. Cavalier Comparison Area was not included in this analysis because of limited data.

Few observations and high variability in five of six focal species limited analysis for this report.

With the exception of Black Rockfish, all other focal species had too few observations to detect differences in density by site or year, so statistical analyses were not conducted. Cavalier Comparison Area was not included in any focal species analysis because of limited data. China Rockfish, Cabezon and Lingcod have density timeseries presented for the marine reserve and Schooner Creek Comparison Area, but Yelloweye Rockfish were not observed in five years of SCUBA fish surveys at either site. Greater densities of Black Rockfish were observed in the Schooner Creek Comparison Area than the Cascade Head Marine Reserve. There were no yearly trends in Black Rockfish density detected at either site.

2.2 Conclusions

This is the first report summarizing SCUBA fish monitoring efforts at the Cascade Head Marine Reserve

The Ecological Monitoring Report 2012-2013 (ODFW 2015) did not include any analysis or summary of SCUBA monitoring efforts at the Cascade Head Marine Reserve because SCUBA monitoring efforts began in 2013. The first successful SCUBA fish transects did not take place until 2014, and only at two sites - the marine reserve and Schooner Creek Comparison Area, because of challenges with visibility. Few fish transects were completed at the Cavalier Comparison Area site over the three years of monitoring efforts. Even though data were somewhat limited, the fish community composition observed with SCUBA monitoring efforts were similar across sites and years. Black Rockfish and Kelp Greenling were the most abundant species at the Cascade Head Marine Reserve and Schooner Creek Comparison Area.

Poor visibility and few observations limited the ability to detect changes and trends in nearshore fish populations with SCUBA Fish surveys.

This report documents the limited success of SCUBA fish survey efforts at the Cavalier Comparison Area because of challenges with visibility that resulted in only seven fish transects over three years of data collection efforts. These limited transects prevented us from including Cavalier in aggregate and focal species abundance analyses. Even at the Cascade Head Marine Reserve and Schooner Creek Comparison Area there were few observations and high variability of many species preventing statistical analysis to detect changes between sites or trends through time. More schooling species were observed in the Schooner Creek Comparison Area, likely driving the differences in aggregate abundance with the marine reserve. Schooling species are highly variable with abundances that occur with greater spatial variability than the size of our sampling unit (i.e. 60m^2 transect). This leads to high confidence intervals surrounding mean density estimates, and suggest that identifying temporal changes in abundance of these species will be challenging. Our results to date support this conclusion. On average, a 2.7 fold difference in density was needed to detect significant differences in density. Kelp Greenling was one of the most abundant species observed at both sites, and is a more homogeneously distributed fish, therefore it would be a likely candidate for detecting change over time with SCUBA monitoring data. Few observations of solitary demersal rockfish with this tool at this site, suggest detecting change over time in these species would be challenging given current survey efforts.

A move toward permanent transects at the Cascade Head Marine Reserve and its associated comparison areas is needed for future SCUBA surveys to be effective.

Focusing dive survey efforts on permanent transects at each site would reduce spatial variability, and increase the ability to detect temporal variability, with a focus on comparing rates of change over time inside and outside the marine reserve. With a better understanding of the sea states, visibility and communities of nearshore reefs, we can now select the appropriate locations to re-focus monitoring efforts, maximizing efficiency in data collection and power to detect change over time. Effort should focus on the Cascade Head Marine Reserve and Schooner Creek Comparison Area only, unless a move to permanent transects is made. Three years of effort resulted in limited success with visibility for fish surveys at the Cavalier Comparison Area, which suggests limited use of this monitoring location for visual tools.

3 SCUBA Fish Methods

SCUBA fish sampling is conducted in the Cascade Head Marine Reserve, Schooner Creek and Cavalier Comparison Areas following PISCO protocols, modified for diving safety in Oregon. Monitoring began in the Cascade Head Marine Reserve and Schooner Creek Comparison Area in 2014, successful sampling of Cavalier Comparison Area occurred in 2017. In the initial years there was a strong focus to place more sampling effort in the reserve to ensure adequate characterization of baseline conditions prior to closure. Since then, sampling effort targeted 6 days for both spring and fall monitoring, splitting effort between the marine reserve and its comparison areas based on ocean conditions. Surveys typically occur during spring and fall due to visibility constraints associated with upwelling conditions; survey dives begin at least one hour after sunrise and conclude one hour before sunset to avoid the crepuscular period. Two to three replicate transects are completed during a given dive,spaced 2m apart, at similar depths, depending on bottom time. All fish are identified to species and total length (cm), except small sculpins and gobies < 8 cm.

The purpose of fish sampling is to generate densities of select species at depths between 10-20m. Multiple transects are completed across three target depths 10, 15 and 20 m. Fish surveys target benthic fishes only - midwater and canopy fishes are not included in Oregon Marine Reserves monitoring. Fish surveys are conducted on separate dives from algae and invertebrate surveys at each site due to time limitations of data collection and to reduce sampling artifacts from diver attraction / repulsion of fishes. Minimal kelp habitat is located in the Cascade Head Marine Reserve and its associated comparison areas, so dive site locations were randomly generated from available habitat within the targeted depth ranges.

The unit of replication is at the transect level. Only fully completed, independent transects were included in analysis. For additional details on data collection, please review documentation in the Methods Appendix.

3.1 Diversity

With SCUBA fish surveys, we explored several concepts related to species diversity at a given site:

species richness
unique, common & rare species
diversity indices
diversity through time

3.1.1 Species Richness

To explore species richness at a given site, we reported total observed species richness and also calculated total estimated species richness.

To report total observed species richness at a given site we used incidence data across all sampling years because each site (reserve or comparison area) likely has a species pool larger than can be sampled in any one year. We excluded unidentified species from the summaries.

To calculate estimated species richness, we used a rarefaction and extrapolation technique as described in Hsieh et al 2016, to calculate the effective number of species at each given site. This is the equivalent of calculating Hill diversity = 0. Hill numbers represent a unified standardization method for quantifying and comparing species diversity across multiple sites (Hill 1973), and they represent an intuitive and statistically rigorous alternative to other diversity indices (Chao et al 2014).

We used the same sampling based incidence data as used to document total observed species richness, using the iNext package in R to estimate the asymptote of the species accumulation curve, or the estimated total number of species observable by SCUBA surveys at a given site. We also calculated confidence intervals associated with these rarefaction and extrapolation curves and can therefore compare across sites to explore similarity of total estimated species richness for a given sampling effort.

3.1.2 Unique, Common, and Rare Species

Richness alone does not sufficiently describe species biodiversity; additionally uniqueness, rarity and common species also shape and define concepts of biodiversity.

As a first step to exploring unique, rare and common species we generated species count tables. These tables exclude the unidentified individuals. The species count tables include a total count for each species summed for all years by site, and for each year-site combination, as well as mean frequency of occurrence across all samples. This information can tell us both about how frequently the species is observed, as well as its relative abundance.

From the species count tables we identified rare species, as those with a frequency of occurrence of 10% or less (Green and Young 1993), and common species as those with a frequency of occurrence greater than 50% (in other words, the species is observed on one out of every two transects). We also identified species that were unique to each marine reserve and comparison area.

3.1.3 Diversity Indices

To gain additional insight into species diversity, we explored several diversity indices by comparing Hill diversity numbers across sites using the iNEXT diversity package in R (Hsieh et al 2016). Hill numbers are parameterized by a diversity order q, which determines the measures’ sensitivity to species relative abundances (Hsieh et al 2016). Hill numbers include the three most widely used species diversity measures; species richness (q = 0), Shannon diversity (q=1) and Simpson diversity (q=2) (Hsieh et al 2016). We used sampling based incidence data with the iNext package in R, to plot rarefaction and extrapolation curves for each Hill number, and compare results across sites. We also calculated 95% confidence intervals associated with these rarefaction & extrapolation curves.

3.1.4 Diversity Through Time

Finally we explored how diversity changed through time. First we plotted each species yearly rarefaction curve against the total cumulative rarefaction curve for all years combined to determine if we had sampled appropriately to compare species diversity from year to year. When our sampling effort was not adequate to compare across years, we pooled data from all years to compare average daily diversity using an anova. This would provide useful information about site diversity for an average sampling day of effort.

All analyses and graphs were created in R v4.0.2, using the iNEXT and Vegan packages.

3.2 Community Composition

We focused our community composition analysis on the question of whether variation in fish density was driven by spatial (site) or temporal (year) factors. We did this through both data visualizations with non-multidimensional scaling (nMDS) plots and with statistical tests such as principal coordinates analyses (PCO), multivariate ANOVA tests (PERMANOVA), and dispersion tests (PERMDISP). In addition to site and year, we also explored several species-specific drivers of variation.

To explore variation by site and year, we used fish density data collected on SCUBA fish transects with a log transformation to downweight dominant species without overly enhancing importance of rare species (Clarke et al. 2006). Densities were calculated from SCUBA fish count data (# fish / area) so a similarity-based resemblance matrix was selected. A dummy variable (=1) was added prior to creating the resemblance matrix due to the high prevalence of zeros in the dataset. To visualize the data, we ran a cluster analysis and generated nMDS plots by site and year.

To test the statistical significance in our data of variation by site and year we ran a permutational analysis of variance (PERMANOVA), using a mixed model with site and year as fixed effects factors. Initial explorations of the first two years of data resulted in no apparent trends by depth among the three targeted depths, therefore depth was considered a random effect, and nested under site. To explore if any significant results of the PERMANOVA were related to true differences in location or differences in dispersion of samples (either by site or year to year), we ran a PERMDISP, a distance based test for homogeneity of multivariate dispersions for any factors of significance from the PERMANOVA (Anderson and Walsh 2013). If a factor was significant in the PERMANOVA but not the PERMDISP, then it can be inferred that the significance is related to a location effect, but not a dispersion effect. If the factor is also significant in the PERMDISP, then significance in the PERMANOVA is related to dispersion, but there may also be a location effect.

Beyond site and year, we explored species-specific drivers in the variation of fish community structure. We extended our data visualization, by performing a vector analysis of fish species in the community, selecting only the species with > 0.5 Pearson correlations (Hinkle et al. 2003). We then generated density plots of the identified species to visualize their relationship to site or year. To better understand how these species contributed to variation in the data, we ran a principal coordinates (PCO) analysis, using a Bray-Curtis resemblance matrix, which provides information on the percent of variation explained by each axis.

All analyses and graphs were made in PRIMERe version 7 with PERMANOVA extension.

3.3 Abundance

We explored changes in aggregate and focal species densities by site and year with generalized additive mixed models (GAMMs). We modeled densities using raw count data with the offset of transect area (Maunder and Punt 2004, Zuur 2012) and a negative binomial distribution. GAMMs were chosen to account for non-linear trends in density (or size) by year detected in preliminary data exploration (Veneables and Dichmont 2004, Zuur et al. 2009). GAMMs were fitted using the mgcv package in R. Site was treated as a fixed categorical variable, while Year was continuous and smoothed with the thin-plate smoother ‘s()’ (Zuur et al 2009; Zuur 2012), grouped by Site, and k was restricted to 3 knots to prevent over-fitting. Depth-Bin was included as a random effect in the model to account for the sampling design targeting three fixed depths. We limited our modeling exercise to focus on Site and Year as these are two of the primary questions of interest. For species with very low densities across most sites and years, no statistical analyses were conducted as the data violated assumptions of the model framework.

Specifically we analyzed aggregate density and species-specific density for focal species only with data from the Cascade Head Marine Reserve and Schooner Creek Comparison Area because of low sample sizes at the Cavalier Comparison Area.

There are six focal fish species for the Oregon Marine Reserves Ecological Monitoring Program:

Black Rockfish; Sebastes melanops
Blue/Deacon Rockfish; Sebastes mystinus / S. diaconus
China Rockfish; Sebastes nebulosus
Yellow-eye Rockfish; Sebastes ruberrimus
Cabezon; Scorpaenichthys marmoratus
Lingcod; Ophiodon elongatus

These species were chosen based on their ecological, economic or management importance. For more information please refer to the methods Appendix detailing focal species selection. Additional species beyond focal species were included for analysis when they were identified in community analysis as being an important driver of variation.

All analyses and data plots were created in R v4.0.2, using the mgcv (version 1.8-36), mgcViz and gratia packages. Models were structured in R as follows:

Density = mgcv::gam(Counts ~ Site + s(Year, by = Site, k = 3) + s(Depth-Bin, bs = “re”), offset = log(Transect Area), family = nb)

4 Cascade Head Results

SCUBA fish sampling efforts at Cascade Head and its comparison areas resulted in three years of data collection, where varying sample sizes were collected per year (Fig. 2). Sampling efforts resulted in more transects completed in the marine reserve than in the comparison areas. The Cavalier Comparison Area was not sampled in 2014.

Fig. 2: SCUBA fish monitoring efforts at the Cascade Head Marine Reserve and its comparison areas resulted in varied sample sizes over the three years of data collection. Sample size is represented in number of transects.

Table 2: Cascade Head SCUBA Fish Monitoring Efforts

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4.1 Diversity

4.1.1 Species richness

Fish species richness is most similar between the Cascade Head Marine Reserve and Schooner Creek Comparison Area

Over the four years of sampling with SCUBA fish surveys, a total of 11 species (or species groups) were observed in the Cascade Head Marine Reserve (Table 3). The Schooner Creek Comparison Area had similar total number of observed species (n = 14), and the Cavalier Comparison Area had fewer total observed species (n = 4). These observed numbers of species richness are similar to the estimated numbers of total species richness (Table 3)

library(kableExtra)
pna <- data.frame(Area = c("Cascade Head Marine Reserve", 
                           "Schooner Creek Comparison Area",
                           "Cavalier Comparison Area"), 
                  Observed_Richness = c("11","14", "4"), 
                  Estimated_Richness = c("12","20", "4"), 
                  LCL = c("11","15", "4"),
                  UCL = c("22", "53", "11"))


  kbl(pna, caption = "Table 3: Observed and estimated fish species richness by site with lower (LCL) and upper (UCL) 95% confidence limits") %>% 
  kableExtra::kable_classic()

Table 3: Observed and estimated fish species richness by site with lower (LCL) and upper (UCL) 95% confidence limits
Area	Observed_Richness	Estimated_Richness	LCL	UCL
Cascade Head Marine Reserve	11	12	11	22
Schooner Creek Comparison Area	14	20	15	53
Cavalier Comparison Area	4	4	4	11

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Species rarefaction curves highlight that for small samples sizes, including those for any given year, the species richness between Cascade Head and Schooner Creek is most similar, and fewer species are observed at Cavalier (Fig. 3). Only the rarefaction curve at the Cascade Head Marine Reserve appears to level off, suggesting saturation in species richness with this tool at this site. More sampling is needed at both the comparison areas to reach saturation.

Fig. 3: Species rarefaction curves for the Cascade Head Marine Reserve and its associated comparison areas. Data are pooled across all years of sampling for each site.

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4.1.2 Unique, common and rare species

Similarities in common species but differences in unique and rare species between the Cascade Head Marine Reserve and its associated comparison areas.

The Cascade Head Marine Reserve and Cavalier Comparison Area did not have any unique species observed on SCUBA surveys, but the Schooner Creek Comparison Area had three - Pile Surfperch, China and Canary Rockfish. Kelp Greenling was the only common species at Cascade Head Marine Reserve while Black Rockfish was the only common species at both comparison areas. The marine reserve (n= 6) and Schooner Creek (n=9) had similar numbers of rare species (Tables 4 and 6). No rare species were observed at Cavalier Comparison Area (Table 8).

Many of the other benthic fish species were not caught frequently resulting in low pooled counts. Not all species were observed each year, for a summary of species counts over the years by site please see tables below.

Pooled species counts across all years and species counts by individual sampling year are included in the following tables:

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4.1.2.1 Cascade Head Marine Reserve

Fig. 4: Relative frequency of occurrence of fish species observed at the Cascade Head Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

4.1.2.2 Schooner Creek Comparison Area

Fig. 4: Relative frequency of fish species observed at the Cascade Head Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

4.1.2.3 Cavalier Comparison Area

Fig 4: Relative frequency of fish species observed at the Cascade Head Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

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4.1.3 Diversity Indices

The Cascade Head Marine Reserve has similar diversity indices to the Schooner Creek Comparison Area, but has higher effective numbers of fish species than the Cavalier Comparison Area

Across diversity indices, the effective number of fish species is similar for the Cascade Head Marine Reserve and the Schooner Creek Comparison Area. However the effective number of fish species for the Cavalier Comparison Area is lower across all indices than the Cascade Head Marine Reserve (Fig. 5).

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Fig. 5: Comparing effective number of fish species (Hill diversity numbers) across the Cascade Head Marine Reserve and its associated comparison areas fom SCUBA fish transects. Hill numbers include the three most widely used species diversity measures; species richness (q = 0), Shannon diversity (q=1) and Simpson diversity (q=2) (Hsieh et al 2016).

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4.1.4 Diversity through time

We did not get enough samples to evaluate change in species diversity through time at the Cascade Head Marine Reserve and its associated comparison areas.

Species rarefaction curves by year for each site indicated that we did not sample enough on a yearly basis to compare changes in mean species richness through time (Fig. 6-8).

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For an average SCUBA transect, fish species diversity does not differ between the Cascade Head Marine Reserve and either of its associated comparison areas.

When comparing mean species richness for an average SCUBA transect, there was no difference between the marine reserve and either of its associated comparison areas (F.0.628, p>0.05) (Fig. 9).

Fig. 9: Mean species richness by site with 95% confidence intervals at the Cascade Head Marine Reserve and its associated comparison areas from SCUBA fish transects.

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4.2 Community Composition

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4.2.1 Variation by Site and Year

Fish community composition was similar at the Cascade Head Marine Reserve and its comparison areas, although more variation was observed at Schooner Creek Comparison Area than the marine reserve.

There was no coherent structuring of fish community composition data across sites with SCUBA fish data at the Cascade Head Marine Reserve and its comparison areas (Fig. 10), although a number of transects from the Schooner Creek Comparison Area had higher variability than any other sites. Although the Schooner Creek Comparison Area contained more variable fish communities, overall transects across all sites were more than 70% similar, indicating that the majority of surveys at Schooner Creek Comparison Area were highly similar to other sites.

Fish community composition was similar across years, although more variation was observed in 2014 than any other year.

There was no structuring of fish community composition data across years with SCUBA fish data at the Cascade Head Marine Reserve and its comparison areas. (Fig. 10). Several surveys from 2014 had more variation than observed in any other year, however the majority of all surveys across years were more than 70% similar, indicating that differences between years is not representative of any consistent temporal trend.

Multivariate statistics did not indicate differences by site or year in fish community composition at the Cascade Head Marine Reserve.

PERMANOVA results indicate that none of the main factors or any interactions were significant for fish community composition with SCUBA density data (Table 10).

Table 10: PERMANOVA results

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4.2.1.1 Site

Fig. 10: Results from nMDS plots with SCUBA fish data, demonstrating similarity in fish community composition at the Cascade Head Marine Reserve and its comparison areas. See separate tabs for site and year.

4.2.1.2 Year

Fig. 10: Results from nMDS plots for SCUBA fish data, demonstrating similairity in fish community composition at the Cascade Head Marine Reserve and its comparison areas. See separate tabs for site and year

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4.2.2 Other drivers of variation

Schools of Black, Canary, and Yellowtail Rockfish drive the majority of variation in fish density data at the Cascade Head Marine Reserve and its associated comparison areas

We explored species-specific drivers of variation, and found that Black, Canary, and Yellowtail Rockfish were highly correlated with community structure (Fig. 11). Principal coordinate analysis revealed that ~72% of the variation is explained by density of Black Rockfish and 11% of variation is described by Canary and Yellowtail Rockfish. Together the abundance of these three species / species complexes accounts for over 83% of model variability.

Density plots indicate the majority of fish community structure at both Cascade Head Marine Reserve and its comparison areas is driven by the density of Black Rockfish, while the presence of Yellowtail and Canary Rockfish was relatively rare with the exception of one sample where both species were found in relatively high densities.

4.2.2.1 PCO Vector Plot

Fig. 11: Results from species correlations and principal coordinate analysis demonstrating that Black, Canary and Yellowtail Rockfish drive variation in community structure at the Cascade Head Marine Reserve and its surrounding comparison areas. See separate tabs for vector and bubble plots. Bubble color / size represents species-specific densities in each sample (species density range indicated in legend).

4.2.2.2 PCO Bubble Plot

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4.3 Aggregate Abundance

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4.3.1 Aggregate Density

Significantly lower aggregate fish density observed at the Cascade Head Marine Reserve than the Schooner Creek Comparison Area.

Aggregate fish density was significantly lower at the Cascade Head Marine Reserve than the Schooner Creek Comparison Area (p < 0.05; Table 11).

No significant yearly trends in aggregate fish density at the Cascade Head Marine Reserve or the Schooner Creek Comparison Area.

There were no significant yearly trends in aggregate fish density at the Cascade Head Marine Reserve or its comparison area (p > 0.05; Table 12).

The random effect of depth was not identified as a significant component of variation (p > 0.05).

GAMM model results can be found in the links below:

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4.3.1.1 Aggregate density timeseries

Fig. 12: Aggregate density timeseries and modeled GAMM results with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison areas. See separate tabs for timeseries and GAMM results.

4.3.1.2 Aggregate density modeled GAMM results

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4.4 Focal Species Abundance & Size

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4.4.1 Black Rockfish, S. melanops

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4.4.1.1 Density

Significantly lower Black Rockfish density observed at the Cascade Head Marine Reserve than the Schooner Creek Comparison Area.

Black Rockfish density was significantly lower at the Cascade Head Marine Reserve than the Schooner Creek Comparison Area (p < 0.05; Table 13).

No significant yearly trends in Black Rockfish density at the Cascade Head Marine Reserve or Schooner Creek Comparison Area.

There were no significant yearly trends in Black Rockfish density at the marine reserve or its comparison area (p < 0.05; Table 14).

The random effect of depth was not identified as a significant component of variation (Table 14).

GAMM model results can be found in the links below:

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4.4.1.1.1 Black Rockfish Density Timeseries

Fig. 13: Black Rockfish density timeseries and GAMM model results with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison area. See separate tabs for timseries and GAMM results.

4.4.1.1.2 Black Rockfish Density Modeled GAMM Results

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4.4.2 Blue/Deacon Rockfish, S.mystinus / S.diaconus

4.4.2.1 Density

Too few observations of Blue/Deacon Rockfish to detect differences in density by site or year.

Densities of Blue/Deacon Rockfish were very low across all sites and years (Fig. 14), so statistical analyses were not conducted.

4.4.2.1.1 Blue/Deacon Rockfish Density Timeseries

Fig. 14: Blue/Deacon Rockfish density timeseries with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison area.

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4.4.3 China Rockfish, S. nebulosus

4.4.3.1 Density

Too few observations of China Rockfish to detect differences in density by site or year.

Densities of China Rockfish were very low across all sites and years (Fig. 15), so statistical analyses were not conducted.

4.4.3.1.1 China Rockfish Density Timeseries

Fig. 15: China Rockfish density timeseries with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison area.

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4.4.4 Yelloweye Rockfish, S.ruberrimus

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4.4.4.1 Density

No observations of Yelloweye Rockfish detected in three years of SCUBA fish surveys.

No observations of Yelloweye Rockfish were observed in any survey year at the Cascade Head Marine Reserve or Schooner Creek Comparison Area, so statistical analyses were not conducted.

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4.4.5 Cabezon, Scorpaenichthys marmoratus

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4.4.5.1 Density

Too few observations of Cabezon to detect differences in density by site or year.

Densities of Cabezon were very low across all sites and years (Fig. 16), so statistical analyses were not conducted.

4.4.5.1.1 Cabezon Density Timeseries

Fig. 16: Cabezon density timeseries with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison area.

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4.4.6 Lingcod, Ophiodon elongatus

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4.4.6.1 Density

Too few observations of Lingcod to detect differences in density by site or year.

Densities of Lingcod were very low across all sites and years (Fig. 17), so statistical analyses were not conducted.

4.4.6.1.1 Lingcod Density Timeseries

Fig. 17: Lingcod density timeseries with 95% confidence intervals, at the Cascade Head Marine Reserve and its associated comparison area.

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4.5 Additional Species Density

Both Canary and Yellowtail Rockfish were identified by the community analysis as important drivers of variation. However sample sizes of both species were too low to detect differences in density by site and year. See species count tables for counts by year (Tables 4-9).

5 References

Anderson M.J., Walsh D.C.I. 2013. PERMANOVA, ANOSIM, and the Mantel test in the face of heterogeneous dispersions: What null hypothesis are you testing? Ecological Monographs 83(4): 557-574.

Chao A., Gotelli N.J., Hsieh T.C., Sander E.L., Ma K.H., Colwell R.K., Ellison A.M. (2014) Rarefaction and extrapolation with Hill numbers: A framework for sampling and estimation in species diversity studies. Ecol Monogr 84:45–67

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### This can be a useful function to play a sound at the end of a long script

#beepr::beep()