Diablo Canyon power plant site ecological study Quarterly Report no. 17: July 1 - September 30, 1977

During the quarter a total of 38 random 30-m2 and 152 random 1/4-m2 subtidal stations were surveyed. Red abalone, Haliotis rufescens, densities remained very low. There was a continued decline in densities of giant red sea urchins, Strongylocentrotus franciscanus, in Diablo Cove as well as the North Control area. The annual shore census of bull kelp, Nereocystis luetkeana, revealed the lowest number of plants in the surface canopy in Diablo Cove since 1973. The subtidal station data supported this observation. Sea otter, Enhydra lutris, observations were continued. A small group of otters continued to raft in the Cove east of Lion Rock. Some of these otters probably forage as far south as South Cove. The survey of 11 random intertidal stations completed our Upwelling sampling effort. (16pp.

Diablo Canyon power plant site ecological study Annual Report July 1, 1976 - June 30, 1977 and Quarterly Report no. 16 April 1, 1977 - June 30, 1977

More stations were surveyed during this report period than during any previous period. A total of 818 mandays was spent surveying 18 permanent and 67 random subtidal stations, 19 permanent and 50 random intertidal stations, and 64 sportfish catch-per-unit-of-effort stations, as well as conducting corollary laboratory work. In the subtidal areas, Laminaria dentigera and Pterygophora californica, both important subsurface kelp species, increased in their combined total numbers from the 1976 survey. However, Nereocystis luetkeana, the bull kelp, declined substantially in all study areas. Population trends of many of the dominant subtidal macro-invertebrates have varied depending on the species and on the type of method utilized. Regression analyses have been performed on selected species for numbers versus depth. Red algal abundance and diversity appear to have increased in both subtidal study areas. Of the three observation areas, sea otters were observed least frequently in Diablo Cove. However, there continues to be fresh evidence of otter foraging within Diablo Cove. Several seasons' data for intertidal algae and invertebrates have been summarized for one study area. While the algae biomass shows a fairly clear seasonality of abundance, the trends in numbers of the six invertebrate species considered are not as well defined. Because of high variability in the data, the sportfish catch-per-unit-of-effort and hook-and-line study was cancelled in December. Populations of intertidal red and black abalones, Haliotis rufescens and H. cracherodii, respectively, appear to have remained fairly stable during the 1976-77 period. Two other ancillary studies were also terminated during this period: interviews of commercial abalone and urchin fishermen, and observations of foam in Diablo Cove. (107pp.

Diablo Canyon power plant site ecological study Quarterly Report no. 7; January 1 - March 31, 1975

During the period January 1 - March 31, 1975 we relocated and remarked five permanent subtidal stations and surveyed 28 random and two permanent intertidal stations. We failed to find a single giant red sea urchin, Strongylocentrotus franciscanus, around station 16 during a dive in March. Abalone, Haliotis spp., numbers decreased at random intertidal stations in North Diablo Cove and the North Control Area. The commerical sea urchin fishery was inactive, while the commerical red abalone, H. rufescens, fishery continued to operate around Pecho Rock. Counts of sea otters south of Point Buchon increased significantly, 20 to 30 otters are now feeding just north of Pecho Rock. Eight random fishery stations in Diablo Cove, Lion Rock Cove and the North Control Area yielded a substantial increase in catch-per-unit-of-effort. (15pp.

Diablo Canyon power plant site ecological study; Quarterly Report No. 11; January 1 - March 31, 1976

Permanent subtidal stations 6, 11 and 16 were surveyed. Appreciable increases in densities of one species of brown algae and five species of macroinvertebrates were noted at station 6. Winter surveys of random and permanent intertidal stations were completed. There was little or no change in black and red abalone, Haliotis cracherodii and H. rufescens, densities at the various random study areas. There was a noticeable increase in black abalone numbers at permanent station 2A located in North Diablo Cove. Three new permanent stations were established and counts of abalone completed. Approximately 100 sea otters, Enhydra lutris, have moved from the Point Buchon area to the area around Pecho Rock. We fished at 13 random stations in Diablo Cove and five stations in North Cove and North Control to determine the catch rate of common sport fishes. A good percentage of the 1975 bull kelp, Nereocystis luetkeana, population weathered the winter storms. We calculated an approximate 18% over-wintering survival rate. Daily observations of foam in Diablo Cove continued; large amounts of piled-up foam have been observed during low tides in the South Diablo intertidal during periods of northwesterly winds. On a recent reconnaissance dive in Intake Cove, fish numbers appeared to be on the increase and visibility appeared to be improving. (15pp.

Diablo Canyon power plant site ecological study Quarterly Report no. 10; October - December 31, 1975

Field work during the quarter included surveys of permanent and random subtidal and intertidal stations. At permanent subtidal stations densities of the brown algae Laminaria and Nereocystis decreased as did densities of giant red sea urchins, Strongylocentrotus franciscanus. Counts of small invertebrates within one-quarter meter square (1/4-m2) quadrats at random subtidal stations were begun. A total of 32 quadrats was completed. Balanophyllia elegans was the most abundant and most common animal encountered. The annual surface count of bull kelp (Nereocystis) was not possible because of the increased density; instead we utilized subtidal counts to estimate the surface canopy. An estimate of 33,000 plants was made for this year's canopy; this compares with a count of 18,000 plants last year. Sampling of random intertidal stations for the Davidson period began; 15 stations were surveyed. In addition, permanent intertidal stations 1, 2 and 3 were surveyed for abalone densities. The sea otter, Enhydra lutris, herd continued to occupy the area around Point Buchon. In November daily observations were initiated on foam location and abundance in Diablo Cove. (13pp.

Mendocino power plant site ecological study, Quarterly Report No. 1; July 1 - September 30, 1971

This report is the first quarterly report submitted in partial fulfillment of Research Contract No. S-1902 between the Department of Fish and Game and the Pacific Gas and Electric Company. Through this contract the Department of Fish and Game is to conduct a pre-operational ecological study to establish a base line inventory of the marine biota with special reference to fish and to abalone, including food chains. Quarterly reports will be followed by annual reports. The first annual report will cover all work from September 1971 through December 1972. Full tables and species lists will be included in each annual report

Diablo canyon power plant site ecological study Quarterly Report No. 1; July 1 - September 30, 1973

The second phase of ecological studies at the Diablo Canyon Power Plant site was initiated in July 1973. The first, phase conducted during 1970-71 involved baseline ecological surveys with special reference to abalone and bony fishes. The objectives of this second phase are to quantitativey monitor abalone and algal communities, including predators and competitors, along permanent intertidal and subtidal transects established during the first phase. During the quarter nine permanent transects were located and marked with new buoys. Surveys on seven of these transects were completed, and the commercial sea urchin and red abalone fisheries operating in the Diablo Cove area were monitored. Sea otter activities between Diablo Cove and Pt. Buchon were recorded to determine the location of the herd and their general food habits. Little evidence of feeding activity has been observed in Diablo Cove. Temperature tolerance studies, began in March 1973 on red abalones, were continued. Problems in obtaining viable abalone larvae hampered this project.(11pp.

Diablo Canyon power plant site ecological study Quarterly Report no. 6; October 1 - December 31, 1974

During the period October 1 - December 31, 1974, a total of six permanent subtidal stations and ten random intertidal stations were surveyed. Red tides and rough seas limited both the commerical abalone and sea urchin fishery activities. Most activity was concentrated between Diablo Cove and Pecho Rock. Divers, however, did work urchin beds as far north as Lion Rock. Sea otter counts have remained relatively stable with almost all individuals being observed north of Lion Rock. Fourteen random fishing stations were completed. Low catch rates reflected fishing success in areas with a heavy brown algae surface canopy. (12pp.

Diablo Canyon power plant site ecological study Quarterly Report no. 22: October 1 - December 31, 1978

Field work for this quarter consisted of completion of random 1/4-m2 subtidal stations from the summer sampling season. In addition, one permanent subtidal station was surveyed. No intertidal stations were surveyed. Sea otters, Enhydra lutris, remained scarce in the vicinity of the power plant. Lab work was comprised of processing subtidal algae samples and sorting and identifying invertebrates from intertidal samples. Analysis of preoperational data for final report proceeded apace. (7pp.

Diablo Canyon power plant site ecological study Quarterly Report no. 19: January 1 - March 31, 1978

Field work was limited to monitoring permanent intertidal and subtidal stations. Only a few stations were surveyed due to a long series of winter storms which produced large seas. Office and laboratory work was devoted to completing computer data sheets for keypunching, completing the 1976/77 annual report and several quarterly reports, and processing the remaining algae samples collected at subtidal and intertidal stations in 1977. Sea otter activity increased in South Cove and Diablo Cove where sea otters were observed on five out of 20 observation days. (11pp.