1 Introduction: Otter Rock 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 Otter Rock began in 2011, one years before harvest restrictions began. Sampling is conducted in the marine reserve and one comparison area, Cape Foulweather (see methods Appendix for additional information about comparison area selection). We conducted four years of sampling at the marine reserve and efforts resulted in three years of sampling at the comparison area. Data across all four years is included in our analysis and synthesis report.
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 Otter Rock Marine Reserve
Fig. 1: Map of SCUBA transect locations at Otter Rock Marine Reserve and Cape Foulweather 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 was similar between Otter Rock Marine Reserve and Cape Foulweather Comparison Area
Fish species diversity was similar between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area. The sites had similar numbers of observed species as well as similar numbers of unique, common, and rare species. Diversity indices were similar between the sites, as was average species diversity per transect.
Fish community composition was similar between sites and years.
There was no apparent structuring of fish community by sites or year at the Otter Rock Marine Reserve and its associated comparison area. Three species drove most of the variation in the fish community composition - Black, Blue/Deacon, and Young of the Year (YOY) Rockfish. The difference between the marine reserve and Cape Foulweather Comparison Area was mostly driven by differences in Black and Blue/Deacon Rockfish. YoY Rockfish were relatively rare except for a few transects at Otter Rock Marine Reserve.
No differences in aggregate density were detected between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area; yearly trends in aggregate density were detected at the Cape Foulweather Comparison Area only.
There was no difference in aggregate fish density between the Otter Rock Marine Reserve and the Cape Foulweather Comparison Area. Aggregate fish density increased through time at the Cape Foulweather Comparison Area. No trends in aggregate density were detected at the Otter Rock Marine Reserve.
Few observations and high variability of focal species limited analysis for this report.
Black Rockfish was the only focal species with sufficient number of observations to test for differences in density by year or site. There were no significant differences in Black Rockfish density between Otter Rock Marine Reserve and Cape Foulweather Comparison Area. Black Rockfish density increased through time at the Otter Rock Marine Reserve. No trends by year were detected at the Cape Foulweather Comparison Area.
2.2 Conclusions
Results of this report consistent with first Ecological Monitoring Report of 2010/2011.
In the first Ecological Monitoring Report of 2010-2011, the SCUBA summary for Otter Rock concluded that the Otter Rock Marine Reserve is characterized by high numbers of Black Rockfish (65%), followed by lower densities of Kelp Greenling (15%) and striped surfperch (10%). This current report, which includes an additional three years of monitoring data, indicates that Black Rockfish comprised 59% of total fish observed and Kelp Greenling 24%. All other species made up less than 5% each of the observed fish counts and is consistent with the 2010/2011 report. Pulse events of YOY recruits drove inter-annual variability in species composition in both reports and were excluded from descriptions of dominant species. Cabezon, Blue/Deacon Rockfish and Canary Rockfish were not observed in the Cape Foulweather Comparison Area during the initial 2011 survey; two of these species (Cabezon and Blue/Deacon Rockfish) have subsequently been observed, highlighting the need for long term monitoring to detect locally rare species.The 2010/2011 report determined that Cape Foulweather was a suitable comparison area because it had similar densities of dominant species and similar species diversity as the marine reserve, and the results of this report support that conclusion.
The ability to detect changes and trends in nearshore fish populations with SCUBA fish surveys is limited.
The Ecological Monitoring Report of 2010-2011 (ODFW 2014) suggested 20 transects per site were needed to characterize the fish community, but after four years of sampling effort at the Otter Rock Marine Reserve and its comparison area, in most years we did not achieved that sample size. We only had the ability to explore change between sites or trends by year with our most abundant species - Black Rockfish. We were able to detect some inter-annual and site differences with this schooling species, but identifying future temporal changes will be challenging because of the high spatial variability of schooling species relative to the size of our sampling unit (i.e. 60m^2 transect). The 2010-2011 report (ODFW 2014) suggests that for more residential homogeneously distributed fishes like Kelp Greenling, we would have greater power to detect temporal change over time, and we did have consistent observations of Kelp Greenling across sites to do so. Unfortunately Kelp Greenling was not chosen for analysis at the species level because it is not a focal species. For other benthic solitary demersal species, such as China Rockfish or Cabezon,we would likely not have the power to detect changes over time due to a combination of low and highly variable densities.
A move toward permanent sites or transects at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area 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.
3 SCUBA Fish Methods
SCUBA fish sampling is conducted in the Otter Rock Marine Reserve and Cape Foulweather Comparison Area following PISCO protocols, modified for diving safety in Oregon. Monitoring began in 2011 with unequal sampling effort; 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 2 days for both spring and fall monitoring, splitting effort between the marine reserve and Cape Foulweather Comparison Area based on ocean conditions. Surveys typically occur during spring and fall due to visibility constraints associated with upwelling. 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 5-15m. Multiple transects are completed across three target depths 5, 10, and 15 m. The Otter Rock Marine Reserve is the shallowest of all marine reserve, and there are no 20 m sites to survey here. 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.
In 2010/2011, scientific divers from Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) selected survey locations with the intent that these sites would be permanent. Selected locations were representative of available rocky reef habitat with kelp, within targeted depth ranges. As monitoring continued, the challenges and safety constraints of diving in Oregon’s nearshore (see Methods Appendix for more details) led to the inevitable need to select alternate locations. Due to unpredictable weather and visibility conditions, sites were selected from randomly generated points based on available rocky reef habitat within targeted depth ranges. These changes resulted in greater spatial coverage of the reef and is more reflective of a stratified random sampling design, rather than one with permanent sites.
The unit of replication is at the transect level. Only fully completed, independent transects were included in analysis. Targeted 5 meter transects from early years of sampling (2010-2011) were included in analysis because of the shallow nature of this site, and several transects from later years occurred at similar depths. 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 transect diversity using an ANOVA
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 factors. Initial explorations of the first two years of data resulted in no apparent trends by depth among the three target depths, therefore depth was considered a random effect in the model. 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 that were significant in 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. Focal species size data were modeled without an offset and after exploration of spatial-temporal auto-correlation of residuals, a gaussian 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.
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 Otter Rock Results
SCUBA fish sampling efforts at Otter Rock and its comparison area resulted in four 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 Cape Foulweather Comparison Area during the years 2011 and 2015. Sampling did not result in data from Cape Foulweather Comparison Area in 2015.
Fig. 2 : SCUBA fish monitoring efforts at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area resulted in varied sample sizes over the four years of data collection. Sample size is represented in number of transects.
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4.1 Diversity
4.1.1 Species richness
Fish species richness is similar across the Otter Rock Marine Reserve and Cape Foulweather Comparison Area.
Over the four years of sampling with SCUBA fish surveys, a total of 12 species (or species groups) were observed in the Otter Rock Marine Reserve (Table 3). The Cape Foulweather Comparison Area had similar total number of observed species (n = 10). These observed numbers of species richness are similar to the estimated numbers of total species richness.
pna <- data.frame(Area = c("Otter Rock Marine Reserve",
"Cape Foulweather Comparison Area"),
Observed_Richness = c("12","10"),
Estimated_Richness = c("14","16"),
LCL = c("12","11"),
UCL = c("31", "47"))
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()| Area | Observed_Richness | Estimated_Richness | LCL | UCL |
|---|---|---|---|---|
| Otter Rock Marine Reserve | 12 | 14 | 12 | 31 |
| Cape Foulweather Comparison Area | 10 | 16 | 11 | 47 |
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Species rarefaction curves highlight that for any samples size, including those for any given year, the species richness among sites is very similar (Fig. 3). The Otter Rock Marine Reserve rarefaction curve appears to level off, suggesting saturation in species richness. The rarefaction curve for Cape Foulweather Comparison Area is continuing to increase suggesting that additional samples are needed to fully describe species richness.
Fig. 3: Species rarefaction curves for the Otter Rock Marine Reserve and Cape Foulweather Comparison Area. 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 unique, common and rare species between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area.
The Otter Rock Marine Reserve had similar numbers of unique species (n = 4) to the Cape Foulweather Comparison Area (n = 2). Buffalo Sculpin (Enophrys bison), Canary Rockfish (S.pinniger), Tubesnout (Aulorhynchus flavidus) and Rock Greenling (Hexagrammos lagocephalus) were unique species to the marine reserve; Red Irish Lord (Hemilepidotus hemilopidotus) and China Rockfish (S.nebulosus) were unique to the comparison area. The Otter Rock Marine Reserve and its comparison area both only had one common species - Black Rockfish. The same number of rare species were observed in both sites (n = 5).
Many of the other target 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:
Table 6: Cape Foulweather Comparison Area Pooled Species Counts
Table 7: Cape Foulweather Comparison Area Species Counts by Year
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4.1.2.1 Otter Rock Marine Reserve
Fig. 4: Relative frequency of occurrence of fish species observed at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area from SCUBA transects. See separate tabs for each site.
4.1.2.2 Cape Foulweather Comparison Area
Fig. 4: Relative frequency of fish species observed at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area from SCUBA transects. See separate tabs for each site.
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4.1.3 Diversity Indices
The Otter Rock Marine Reserve and Cape Foulweather Comparison Area have similar diversity indices for fish
The effective number of species is similar across all three diversity indices for the SCUBA fish community at the marine reserve and Cape Foulweather Comparison Area (Fig. 5). There was strong overlap in the 95% confidence interval estimates between the two survey sites.
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Fig. 5: Comparing effective number of species (Hill diversity numbers) between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area from 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 Otter Rock Marine Reserve and its 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. 6-7).
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For an average SCUBA transect, fish species diversity does not differ between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area.
When comparing mean species richness for an average SCUBA transect, there was no difference between the marine reserve and Cape Foulweather Comparison Area (F.0.136, p > 0.05) (Fig. 8).
Fig. 8: Mean species richness by site with 95% confidence intervals at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area 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 Otter Rock Marine Reserve and Cape Foulweather Comparison Area, and was not influenced by sampling year.
There was no strong structuring of fish community composition data across sites or years with SCUBA fish data at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area. (Fig. 9).
Multivariate statistics indicate differences by site but not year in fish community composition at the Otter Rock Marine Reserve.
PERMANOVA results indicate that site was the only significant factor for fish community composition with SCUBA density data, and none of the interactions were significant (Table 8). While significant, site only accounted for 17% of the variability in the model as opposed to the residuals which explained 76% of model variability. Dispersion tests between sites were not significant, indicating that the significance of site in PERMANOVA model is due to a location effect. While site is significant, the amount of variance explained likely indicates that differences between Otter Rock Marine Reserve and the Cape Foulweather Comparison Area are fairly small.
Table 9: PERMDISP mean dispersions and standard errors by site
Table 11: PERMDISP mean dispersions and standard errors by depth
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4.2.1.1 Site
Fig. 9: Results from nMDS plots with SCUBA fish data, demonstrating similarity in fish community composition at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area. See separate tabs for site and year.
4.2.1.2 Year
Fig. 9: Results from nMDS plots for SCUBA fish data, demonstrating similairity in fish community composition at the Otter Rock Marine Reserve and Cape Foulweather Comparison Area. See separate tabs for site and year
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4.2.2 Other drivers of variation
Schools of Black, Blue/Deacon and Young of the Year (YOY) Rockfish drive the majority of variation in fish density data at the Otter Rock Marine Reserve.
We explored species-specific drivers of variation, and found that Black Rockfish, Blue/Deacon Rockfish and young of the year (YOY) rockfish were driving the majority of variation in the data (Fig. 10). Principal coordinate analysis revealed that ~69% of the variation is explained by density of Black and/or Blue/Deacon Rockfish and 20% of variation is described by young of the year rockfish. Together the abundance of these three species / species complexes accounts for over 89% of model variability.
Among these three species, Black and Blue/Deacon Rockfish were found at both the marine reserve and comparison area, where young of the year (YOY) Rockfish were only observed at Otter Rock Marine Reserve. Due to the inherent patchiness of YOY Rockfish settlement and schooling behavior, it is likely that the observations only at Otter Rock are an artifact of sample size instead of true differences between the reserve and the Cape Foulweather Comparison Area.
4.2.2.1 PCO Vector Plot
Fig. 10: Results from species correlations and principal coordinate analysis demonstrating that Black, Blue/Deacon and Young of the Year (YOY) Rockfish drive variation in community structure regardless of site at the Otter Rock Marine Reserve and its surrounding comparison area. 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
Fig. 10: Results from species correlations and principal coordinate analysis demonstrating that Black, Blue/Deacon and Young of the Year (YOY) Rockfish drive variation in community structure regardless of site at the Otter Rock Marine Reserve and its surrounding comparison area. See separate tabs for vector and bubble plots. Bubble color / size represents species-specific densities in each sample (species density range indicated in legend).
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4.3 Aggregate Abundance
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4.3.1 Aggregate Density
No significant difference in aggregate fish density between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area.
No significant difference in aggregate density between the marine reserve and its comparison area (p > 0.05; Table 13).
Significant yearly trends in aggregate density only at the Cape Foulweather Comparison Area.
There was a significant trend by year in aggregate fish density at the Cape Foulweather Comparison Area (p < 0.05; Fig. 11, Table 14), with an increase from the beginning sampling years through 2019. There was no significant yearly trend at the Otter Rock Marine Reserve (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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4.3.1.1 Aggregate density timeseries
Fig. 11: Aggregate density timeseries and modeled GAMM results with 95% confidence intervals, at the Otter Rock Marine Reserve and its associated comparison area. See separate tabs for timeseries and GAMM results.
4.3.1.2 Aggregate density modeled GAMM results
Fig. 11: Aggregate density timeseries and modeled GAMM results with 95% confidence intervals, at the Otter Rock Marine Reserve and its associated comparison area. See separate tabs for timeseries and GAMM results.
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4.4 Focal Species Abundance
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4.4.1 Black Rockfish, S. melanops
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4.4.1.1 Density
No significant difference in Black Rockfish density between the Otter Rock Marine Reserve and Cape Foulweather Comparison Area
No significant difference in Black Rockfish density between the marine resereve and its comparison area (p > 0.05; Table 15).
Significant yearly trends in Black Rockfish density only at the Otter Rock Marine Reserve.
There was a significant trend by year in Black Rockfish density at the Otter Rock Marine Reserve ( p< 0.05, Fig. 12, Table 16), with an increase from the beginning sampling years through 2019. There was no significant trend at the Cape Foulweather Comparison Area (p > 0.05; Table 16).
The random effect of depth was not identified as a significant component of variation (Table 16).
GAMM model results can be found in the links below:
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4.4.1.1.1 Black Rockfish Density Timeseries
Fig 12: Black Rockfish density timeseries and GAMM model results with 95% confidence intervals, at the Otter Rock 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
Fig 12: Black Rockfish density timeseries and GAMM model results with 95% confidence intervals, at the Otter Rock Marine Reserve and its associated comparison area. See separate tabs for timseries and 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. 13), so statistical analyses were not conducted.
4.4.2.1.1 Blue/Deacon Rockfish Density Timeseries
Fig. 13: Blue/Deacon Rockfish density timeseries with 95% confidence intervals, at the Otter Rock 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. 14), so statistical analyses were not conducted.
4.4.3.1.1 China Rockfish Density Timeseries
Fig. 14: China Rockfish density timeseries with 95% confidence intervals, at the Otter Rock 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 four years of SCUBA fish surveys.
No observations of Yelloweye Rockfish were observed at any site in any survey year at the Otter Rock Marine Reserve and Cape Foulweather 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. 15), so statistical analyses were not conducted.
4.4.5.1.1 Cabezon Density Timeseries
Fig. 15: Cabezon density timeseries with 95% confidence intervals, at the Otter Rock 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. 16), so statistical analyses were not conducted.
4.4.6.1.1 Lingcod Density Timeseries
Fig. 16: Lingcod density timeseries with 95% confidence intervals, at the Otter Rock Marine Reserve and its associated comparison area.
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4.5 Additional Species Density
Unidentified young of the year (YOY) 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.
5 References
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### This can be a useful function to play a sound at the end of a long script
#beepr::beep()