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While the fishing standing stock at Wheeler North Reef has been consistently below the 28 ton requirement, data from last summer s survey showed that it increased by 88% in 2014. This raises the question as to what caused this increase and is it likely to persist?
Shown in this graph is the species composition of the fish standing stock at Wheeler North Reef in 2014. It shows that 5 species (Sand Bass, California Sheephead, Giant Sea Bass, Kelp Bass, and Leopard Shark) accounted for 74% of the standing stock in 2014. The biomass of these five species increased by 2.2 fold from 2013 to 2014. 3
A closer look at these five species provides some insight into the characteristics of their standing stocks at Wheeler North Reef in 2014. The top graph shows the density of each of the five species while the bottom graph shows their average weight in grams. Note that both graphs are plotted on a log scale to show the large differences among species in these attributes. The data plotted in these two graphs show that high numbers of Sand Bass, California Sheephead and Kelp Bass with an average size of about 200 to 500 grams or (1/2 to 1 pound) coupled with a few very large Giant Sea Bass and Leopard Sharks, which accounted for 74% of the standing stock at Wheeler North Reef in 2014. The sizes of all these species indicate that the majority of individuals were adults. The sum of small young of year fish of all 41 species observed contributed < 1% of the standing stock at Wheeler North Reef in 2014. 4
Similar increases in fish standing stock in 2014 were observed at the natural reefs located at San Mateo and Barn. This suggests that the large increase observed in the standing stock at Wheeler North Reef was a regional phenomenon. 5
Sand Bass, California Sheephead, Giant Sea Bass and Kelp Bass accounted for at least 61% of the fish standing stock at all three reefs and their biomass increased by 50% 400% from 2013 to 2014. These data indicate that the large increase in the standing stock of fish observed at Wheeler North Reef in the summer of 2014 reflected regional increases in the biomass of these four species. 6
Oceanographic conditions are known to influence fish standing stocks as individuals move in search of food and favorable environmental conditions. 2014 was a unusually warm year. Data recorded at Scripps Pier show that sea surface temperatures in the summer of 2014 were 2 4 o Chigher than the long term average. There were many sightings of species of tropical fish in the summer of 2014 in southern California that are typically very rare. This included: whale sharks, manta rays, wahoo, blue marlin, puffer fish, chubs. Unusual species sighted during our dive surveys included a broom tail grouper and a fine scale trigger fish. 7
The unusually warm water in summer of 2014 may have influenced the fish standing stocks at Wheeler North Reef, San Mateo and Barn. Sand Bass, California Sheephead, Kelp Bass and Giant Sea Bass, which comprise the majority of the standing stocks at these reefs, are relatively warm water species with tropical affinities. The large increases in the density of these species observed at Wheeler North Reef, San Mateo and Barn in the summer of 2014 may reflect a large scale redistribution of fish in response to changes in food availability and/or environmental conditions. We have seen large temporary spikes in the adult abundance of these species in the past, and it is unknown whether the majority individuals that we observed in summer 2014 will remain in the region when water temperatures decline. 8
The performance standard for fish standing stock requires the Wheeler North Reef to sustain 28 tons of reef fish. This value is based on the estimated reduction in the standing stock of fish in the San Onofre kelp forest that was attributed to SONGS operations in the impact assessment studies overseen by the Marine Review Committee. The Wheeler North Reef has never met this performance standard during the six years of its existence, though it came close last year when there was a regional increase in fish standing stocks. The SONGS coastal development permit requires independent monitoring to determine the reasons why a performance standard is not being met and to develop recommendations for appropriate remedial measures. As per this requirement, we used monitoring data to: (1) investigate the reason(s) why the Wheeler North Reef has consistently failed to meet the performance standard for fish standing stock, and (2) develop potential solutions for ensuring that this performance standard is met in the future. 9
The standing stock of fish on a reef is influenced by a wide variety of factors including ocean climate, fishing and physical attributes of the reef such as its size, rock coverage and topography. The present configuration of the Wheeler North Reef is 174 acres of low relief rock that covers an average of 48% of the bottom. Low relief was chosen to mimic natural reefs in the region including the reef at San Onofre that was damaged by the SONGS operations. Low relief reefs are also more likely to support giant kelp, which was a major objective of the mitigation project. A critical question in assessing the long term performance of the Wheeler North Reef is whether its present configuration is sufficient to sustain 28 tons of fish over the long term. The time series monitoring initiated in 2000 at the start of the Phase 1 Reef and targeted monitoring of high relief reefs in the 2014 provide a quantitative means for evaluating this question. 10
We used data from the 21 rock modules of the Phase 1 Reef to examine the effects of rock coverage on fish biomass. The Phase 1 Reef was constructed in the summer of 1999 and was designed to test two different types of material (quarry rock boulders or rubble concrete) and three bottom coverages that were approximately 40%, 60% and 80%. The reef consists of 56 modules 40 m x 40 m in size that are distributed along a 3.5 km stretch of coast off San Clemente. Data on fish biomass have been collected annually in summer at 21 modules with low, medium and high coverage of rock. These data were used to evaluate the effects of rock cover on fish standing stock.
Plotted here are values for fish standing stock for the low, medium and high coverage rock modules built during Phase 1 since 2000. The values have been scaled to 174 acres, which is the current size of the Wheeler North Reef. These data show the ability of a reef to support at least 28 tons of fish scaled to 174 acres with different rock coverage of the modules. 1. The low rock coverage modules, which are the most similar to the larger Phase 2 mitigation reef, supported at least 28 tons of fish in only 1 of 12 years. 2. In contrast, the high rock coverage modules supported at least 28 tons of fish in 8 of 12 years, 3. The medium rock coverage had an intermediate capacity for fish standing stock as it supported at least 28 tons of fish in 3 of 12 years. These results show the reefs with higher rock coverage support larger fish standing stocks. 12
High relief reefs are known to support more fish biomass than low relief reefs. Because high relief was not considered in the initial design of Wheeler North Reef there are no time series data for quantifying the effects of high relief on fish standing stock. To address this lack of information we collected data during summer 2014 in areas of high relief (2 3 m tall) and in adjacent areas of low relief (< 1 m tall) at two natural reefs in the vicinity of Wheeler North Reef (Two Man Reef and Monument Point). 13
Results from surveys at Two Man Reef and Monument Pt. in 2014 show that fish biomass in areas of high relief (2 3 m tall) was on average 5 to 10 times greater than that in adjacent areas of low relief (< 1 m tall). 14
It is possible that failure of Wheeler North Reef to sustain a fish standing stock of at least 28 tons is not due to some feature of its design, but simply reflects the norm for all reefs (artificial and natural) in the region. This raises the question: What is the capacity of low relief natural reefs to sustain a fish standing stock of at least 28 tons? To answer this question we estimated the standing stock of fish at the natural reefs located at San Mateo and Barn using annual time series data collected since 2000.
Plotted here are annual values for fish standing stock for San Mateo and Barn since 2000. Barn is 328 acres in area whereas San Mateo is 282 acres. Both reefs are generally low relief (< 1 m tall) and their rock coverages of 52% and 47% are very similar to that of Wheeler North Reef (48% rock cover). These data show that Barn supported afish standing stock of at least 28 tons in 7 of 13 years whereas San Mateo supported at least 28 tons of fish in 5 of 13 years. However, as noted above Barn and San Mateo are much larger than Wheeler North Reef. Therefore a pertinent question to answer is How likely is it that Barn and San Mateo would sustain a fish standing stock of 28 tons if they were the same size as Wheeler North Reef? 16
Plotted here are annual values for fish standing stock for San Mateo and Barn using the same data as in the previous slide, but scaled to 174 acres rather than to the actual sizes of the reefs. These data show that when scaled to 174 acres neither of these two natural reefs have consistently supported 28 tons of reef fish biomass. 174 acres of Barn supported at least 28 tons in only 2 of 13 years while 174 acres at San Mateo did it in only 3 of 13 years. These data strongly suggest that 174 acres of low relief natural reefs is not sufficient for sustaining a fish standing stock of at least 28 tons. 17
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To estimate the area of additional reef needed for Wheeler North Reef to sustain a fish standing stock of 28 tons we: 1. Combined the expected future fish standing stock of the existing 174 acre Wheeler North Reef with the expected future standing stock of fish supported by additional new acreage of reef. 2. We did this for different reef designs for the additional new acreage. Data from the rock modules of the Phase 1 Reef collected from 2000 2014 is the longest time series available and it covers a relatively wide range in environmental conditions. 1. We first used these data to predict the number of tons of fish that will be supported by the existing 174 acre Wheeler North Reef in the future with a 90% probability. This turned out to be 15.5 US tons 2. We then used these data to predict the number of additional acres needed to support the remaining 12.5 tons of fish biomass needed to sustain a fish standing stock of 28 tons in the future with a 90% probability. We chose a 90% as the level of certainty in our predictions because we wanted a high assurance in our estimates of the amount of new additional acres needed. Increasing the certainty above 90% would result in more additional acres needed to sustain 28 tons of fish while decreasing the certainty below 90% would result in fewer additional acres needed. 19
Shown here is a summary table with estimates of the number of additional acres of various reef designs that are needed for Wheeler North Reef to sustain a fish standing stock of at least 28 tons. As you can see the amount of addition acreage varies greatly depending on its rock coverage and vertical relief. If new additional acres were designed like the existing Wheeler North Reef (i.e., low relief with low rock coverage), then 175 additional acres would be needed, which would effectively double its current size. It would take approximately half of this area (i.e., 90 acres) if the additional acres were low relief with high rock coverage. By contrast, if the additional acreage consisted of reef that averaged 2.5 m tall and was 100% rock, then only 30 additional acres would be needed. 20
Plans for 2015 are to continue with the monitoring of the performance standards as required by the SONGS coastal development permit. In addition, the CCC staff are in discussions with SCE regarding the need to expand the size of the Wheeler North Reef to ensure that it consistently meets it requirement to support a fish standing stock of at least 28 US tons. 21