An informational summary on elasmobranchs in Elkhorn Slough

Shark angling derbies have been held in Elkhorn Slough since 1946, and archery derbies since about 1973. Elkhorn Slough is an important pupping and breeding area for leopard sharks, Triakis semifasciata, and bat rays, Myliobatis californica, and a spawning or nursery area for many other species of fish. With the establishment of the Monterey Bay National Marine Sanctuary, these derbies, especially the archery derby, have become somewhat controversial. Leopard sharks pup in late spring to early summer, peaking in June. Bat ray pupping peaks in July. Both species breed shortly after pupping. Since 1988, most sharks and rays caught in the angling derbies have been tagged and released under a program developed by Moss Landing Marine Laboratories. No tags have been recovered, suggesting a large population in the area. Prior to the tagging program most sharks and rays taken in the angling derby were rendered at the local tallow works. All sharks and rays that are taken in the archery derby are killed, but relatively few sharks and rays are taken by archers. In 1993,43 sharks and rays were kept by anglers and 13 by archers. The commercial catch of leopard sharks in California averaged 43,000 pounds from 1990 to 1992, and the estimated sport catch of leopard sharks is about 270,000 pounds annually. In comparison, the take during Elkhorn Slough shark derbies is not significant and is not considered a threat to the resource. However, the moral or ethical issue of conducting shark derbies in a marine sanctuary remains. (7pp.

Biomass estimates of Pacific herring, Clupea pallasi, in California from the 1990-91 spawning-ground surveys

The spawning biomass of Pacific herring, Clupea pallasi, estimated from spawning-ground surveys in San Francisco Bay declined to 45,850 tons this season, following a peak of 71,000 tons in the 1989-90 season. This is the first major decline since the 1983-84 El Nino. In Tomales Bay the 1990-91 spawning biomass more than doubled to 779 tons. The spawning biomass has increased the past two seasons, while the fishery has been closed. There was no biomass estimate for Bodega Bay, but an additional 95 tons of herring were caught in Bodega Bay this season. The total herring biomass for the Tomales- Bodega area is a minimum of 874 tons. Humboldt Bay was surveyed by the Department for the first time this season, and spawning biomass was estimated to be 400 tons. January was the month of peak spawning activity in all spawning areas surveyed. In San Francisco Bay, 62% of all spawning occurred alonq the San Francisco waterfront; for the first time there was no significant spawninq in the northern part of the bay. Nearly 70% of the spawning activity in San Francisco Bay occurred on January 3-6, 1991. A total of 3.5 million m2 of eelgrass, Zostera marina, was measured in Tomales Bay this season. The change in eelgrass density this season varied from bed to bed, however the overall density of eelgrass in Tomales Bay declined. (44pp.

Biological characteristics of the catch from the 1990-91 Pacific Herring, Clupea pallasi, roe fishery in California

The Tomales-Bodega Bay catch during the past two seasons has been from the northern part of Bodega Bay, due to the closure of the Tomales Bay fishery. In the Tomales-Bodega Bay area, 4-, 5-, and 6-yr-old herring Clupea pallasi, comprised 79% by number of the 1990-91 season's gill net catch. The number of 4-yr olds (1987 year class) increased to 21% of the gill net catch. Four-yr olds are an indicator of recruitment strength into the gill net fishery. Average length of herring in the Tomales-Bodega Bay area gill net catch decreased due to a shift to younger herring in the catch, as well as, poor growth characteristics during 1990. Herring age and size data obtained from Tomales Bay with a variable mesh research gill net were similar to data from San Francisco Bay obtained with the same net. All age classes were taken and herring ranged in length from 148 mm to 226 mm. In San Francisco Bay, the age composition of the gill net catch was also primarily 4-, 5-, and 6-yr-old herring, which comprised 79% of the catch. In the round haul fishery 2- and 3-yr-old herring dominated, comprising 72% of the catch. The average length of herring in the San Francisco Bay gill net and round haul catches decreased. Both are the lowest recorded average lengths by the respective gear types except for the 1983-84 El Nino season. Observed poor growth characteristics this season are attributed to reduced upwelling off central California in 1990. (26pp.

Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1981-82 spawning ground surveys

The spawning biomass of Pacific herring in San Francisco Bay and Tomales Bay was estimated to be 99,495 tons and 7,149 tons, respectively during the 1981-82 season. This is the highest estimate to date for San Francisco Bay and continues a rising trend in abundance. The Tomales Bay population increased to the highest level in 4 years. (22pp.

Biological characteristics of the catch from 1984-85 Pacific herring, Clupea harengus pallasi, roe fishery in California

In Tomales Bay, 5-, 6-, and 7-yr-old herring, Clupea harengus pallasi, composed 75% by number of the 1984-85 season's catch. In San Francisco Bay, 2-, 3-, and 4-yr-old herring composed 82% by number of the roundhaul catch, and 5-, 6-, and 7-yr-old herring composed 68% by number of the gill net catch. The percent of 4-yr-old herring increased to a record high level in the San Francisco Bay gill net catch. Recruitment of 2-yr-old herring into the San Francisco Bay roundhaul fishery was excellent, with 2-yr-old herring composing 41% of the catch. The growth rate of herring improved in both Tomales and San Francisco Bays, after the period of poor growth during the recent El Nino, when the weight of herring averaged 20% below normal. (23pp.

Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1987-88 spawning-ground surveys

The 1987-88 spawning biomass estimate of Pacific herring, Clupea harengus pallasi, in San Francisco Bay is nearly 69,000 tons. This is the fourth consecutive year that the San Francisco Bay population has increased, after reaching a low point of 40,000 tons in 1984. In Tomales Bay the 1987-88 herring spawning biomass was estimated at 2,061 tons. During the past five seasons, the Tomales Bay spawning biomass has been low in even years and high in odd years, indicating that spawning herring are not returning to Tomales Bay consistently. In San Francisco Bay, over 42,000 tons of herring spawned in January. Similarly, 90% of Tomales Bay herring spawned in January. No spawns were found during March in either bay. For the first time, in San Francisco Bay, no herring spawned in the Belvedere, Tiburon, or Angel Island areas. In addition, herring spawning was found in the Oakland-Alameda area for the first time and over 95% of all spawning occurred in the southern part of San Francisco Bay. During the past six seasons in San Francisco Bay, over 70% of all spawning escapement has been in the southern part of the bay. For the nine seasons prior to that, 94% of all spawning escapement was in the northern part of the bay. (31pp.

Species composition and catch per unit of effort of Monterey Bay surf, pier, and skiff anglers in 1979

In 1979, Monterey Bay sport anglers were sampled for species composition of the catch and catch per unit of effort. A total of 4150 surf, pier, and skiff anglers was interviewed. Catch per hour was 0.71, 0.58, and 1.25 for surf, pier, and skiff anglers, respectively. Barred surfperch, Amphisticus argenteus, totaled 76% of the surf catch. The species composition of the pier catch was dominated by juvenile bocaccio, Sebastes paucispinis; white croaker, Genyonemus lineatus; and walleye surfperch, Hyperprosopon argenteum. The skiff fishery was dominated by sanddabs, Citharichthys spp., and blue rockfish, Sebastes mystinus. The best surf fishing area was between Palm Beach and Sand Dollar Beach in northern Monterey Bay, while Monterey Wharf No. 2 was the best public fishing pier. However, a small privately operated pier inside Moss Landing Harbor had the best catch rate (2.44 fish per h) of all piers sampled. (23pp.

Biomass estimates of Pacific herring, Clupea pallasi, in California from the 1989-90 spawning-ground surveys

The 1989-90 spawning biomass estimate of Pacific herring, Clupea pallasi, from spawning-ground surveys in San Francisco Bay was 71,000 tons, a 5,000 ton increase over the 1988-89 biomass estimate of 66,000 tons. The San Francisco Bay herring biomass has been on an upward cycle since 1984, and results from spawning-ground surveys indicated that the population was at its highest level in eight years. In Tomales Bay the 1989-90 herring spawning biomass estimate was 345 tons. This was the third consecutive poor season. Herring have nearly abandoned Tomales Bay, and reduced freshwater in flows due to the current drought condition in California were the probable cause for the change in spawning behavior. An additional 445 tons were found in Bodega Bay by hydroacoustic surveys. The total herring biomass estimate for Tomales-Bodega area was 790 tons. January was the month of peak spawning activity in San Francisco Bay, with 30,000 tons of herring spawning during the month. In Tomales there was only one spawning run; it occurred on January 31, 1990. In San Francisco Bay, 67% of all spawning occurred along the San Francisco waterfront, and only 6% of all spawning activity was in the northern part of the bay. No spawning was found near Tiburon, Belvedere, Richmond, Berkeley, Candlestick Point, Sierra Point, Oyster Point, or Coyote Point. A total of 3.5 million m2 of eelgrass, Zoster marina, was measured in Tomales Bay this season, a decline of about 10% over the past two seasons. Eelgrass density kg/m2 did not change significantly this season. (34pp.

Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1980-81 spawning ground surveys

The spawning biomass of Pacific herring in San Francisco Bay and Tomales Bay was estimated to be 65,441 tons and 5,583 tons, respectively during the 1980-81 season. This is the highest estimate to date for San Francisco and continues a rising trend in abundance. The Tomales Bay population has fluctuated around an annual mean of 6,000 tons since 1973. (24pp.

Biological characteristics of the gill net catch from the 1989-90 Pacific herring, Clupea pallasi, roe fishery in California

The Tomales-Bodega Bay catch this season was from northern Bodega Bay, and the possibility that this season's catch may be from a different stock must be considered. In the Tomales-Bodega Bay area, 5- through 8-yr-old herring, Clupea pallasi, comprised 89% by number of the 1989-90 season's gill net catch. Recruitment of the 1986 year class (4-yr olds) was relatively poor, comprising only 9% of the gill net catch by number. Average length of the Tomales-Bodega Bay area gill net catch increased to 204 mm BL because the number of 3- and 4-yr olds in the catch decreased to 11%, the lowest level since the 1982-83 season. The average weight at age of 4-through 8-yr-old herring did not change significantly this season. In San Francisco Bay, for the first time since the 1982-83 season, 5-, 6-, and 7-yr-old herring were the dominant age groups comprising 79% by number of the gill net catch. This reverses a trend toward younger and smaller herring in the gill net catch. The average length of herring in the San Francisco Bay gill net catch increased to 196 mm BL. The change in the size and age composition is attributed to better enforcement of the 2 1/8 in. gill net mesh regulation. The sex ratio of the gill net catch also improved. Females comprised 53% of the catch in both San Francisco and Tomales bays. (19pp.