Abundance and distribution of California sea lions (Zalophus californianus) in central and northern California during 1998 and summer 1999

The abundance and distribution of California sea lions (Zalophus californianus) in central and northern California was studied to allow future evaluation of their impact on salmonids, the ecosystem, and f isheries. Abundance at-sea was estimated by using the strip transect method from a fixed-wing aircraft with a belly viewing port. Abundance on land was estimated from 126-mm-format aerial photographs of animals at haulouts between Point Conception and the California−Oregon border. The sum of these two estimates represented total abundance for central and northern California. Both types of survey were conducted in May−June 1998, September 1998, December 1998, and July 1999. A haulout survey was conducted in July 1998. The greatest number of sea lions occurred near Monterey Bay and San Francisco Bay for all surveys. Abundance was high in central and northern California in 1998 when warm water from the 1997−98 El Niño affected the region and was low in July 1999 when cold water La Niña conditions were prevalent. At-sea abundance estimates in central and northern California ranged from 12,232 to 40,161 animals, and haulout abundance was 13,559 to 36,576 animals. Total abundance of California sea lions in central and northern California was estimated as 64,916 in May−June 1998, 75,673 in September 1998, 56,775 in December 1998, and 25,791 in July 1999. The proportion of total abundance to animals hauled-out for the four complete surveys ranged from 1.77 to 2.13, and the mean of 1.89 was used to estimate a total abundance of 49,697 for July 1998. This multiplier may be applicable in the future to estimate total abundance of California sea lions off central and northern California if only the abundance of animals at haulout sites is known.

Feeding habits of European hake (Merluccius merluccius) in the central Mediterranean Sea

European hake (Merluccius merluccius) is an important predator of deeper shelf-upper slope Mediterranean communities. It is a nectobenthic species distributed over a wide depth range (20−1000 m) throughout the Mediterranean Sea and the north east Atlantic region (Fisher et al., 1987). Notwithstanding the ecological and economic importance (Oliver and Massutí, 1995) of hake in the Mediterranean, many aspects of its biology (e.g., recruitment and reproduction), due to multiple spawning (Sarano, 1986) and the current state of exploitation, are poorly understood (Arneri and Morales-Nin, 2000).

Diet of oceanic loggerhead sea turtles (Caretta caretta) in the central North Pacific

Diet analysis of 52 loggerhead sea turtles (Caretta caretta) collected as bycatch from 1990 to 1992 in the high-seas driftnet fishery operating between lat. 29.5°N and 43°N and between long. 150°E and 154°W demonstrated that these turtles fed predominately at the surface; few deeper water prey items were present in their stomachs. The turtles ranged in size from 13.5 to 74.0 cm curved carapace length. Whole turtles (n =10) and excised stomachs (n= 42) were frozen and transported to a laboratory for analysis of major faunal components. Neustonic species accounted for four of the five most common prey taxa. The most common prey items were Janthina spp. (Gastropoda); Carinaria cithara Benson 1835 (Heteropoda); a chondrophore, Velella velella (Hydrodia); Lepas spp. (Cirripedia), Planes spp. (Decapoda: Grapsidae), and pyrosomas (Pyrosoma spp.).

Forty Years of Winter: Cetaceans Observed During the Southbound Migration of Gray Whales, Eschrichtius robustus, Near Granite Canyon, Central California

From December to February in most years from 1967 to 2007, observers counted gray whales, Eschrichtius robustus, from shore sites south of Carmel in central California. In addition to gray whales, other cetacean species were also recorded. These observations were summarized and compared among survey platforms and to ocean conditions. Eleven cetacean species were identified including eight odontocete species (killer whale, Orcinus orca; Pacific white-sided dolphin, Lagenorhynchus obliquidens; common dolphin, Delphinus spp.; bottlenose dolphin, Tursiops truncatus, northern right whale dolphin, Lissodelphis borealis; Risso’s dolphin, Grampus griseus; Dall’s porpoise, Phocoenoides dalli; and harbor porpoise, Phocoena phocoena) and three mysticete species (humpback whale, Megaptera novaeangliae; minke whale, Balaenoptera acutorostrata; and blue whale, Balaenoptera musculus). As expected, the detection of certain species among survey platforms (shore-based census watches, 25-power “Big Eye” binocular watches, and aerial surveys) was limited by species surfacing behavior and/or bathymetric preference. Comparisons among the shore-based census efforts showed a significant difference in sightings rates from 1967–84 (n = 14, mean = 0.11, SD = 0.11) to 1985–2007 (n = 11, mean = 1.48, SD = 0.47; t-Test: p < 0.001, df = 23). The warm period observed during the 1990’s may partially explain the increase in sighting rates and diversity of species observed at the census site compared to the much cooler temperatures of the 1970’s.

Length-weight Relationships of Dolphinfish, Coryphaena hippurus, and Wahoo, Acanthocybium solandri: Seasonal Effects of Spawning and Possible Migration in the Central North Pacific

Weight-on-length (W-L) relationships for 2,482 dolphinfish, Coryphaena hippurus, and 1,161 wahoo, Acanthocybium solandri, were examined. Data on fork length, whole (round) weight, and sex were collected for dolphinfish at the Honolulu fish auction from March 1988 through November 1989. Unsexed weight and length data for wahoo were collected at the auction from July 1988 through November 1989. We also used sex specific weight and length data of 171 wahoo collected during 1977–1985 research cruises for analysis. Coefficients of W-L regressions were significantly different between the sexes for dolphinfish. Coefficients did not significantly differ between the sexes for wahoo based on research cruise data. In a general linear model evaluating month as a categorical factor, month was significant for female dolphinfish, male dolphinfish, and wahoo with sexes pooled. W-L and length-on-weight (L-W) relationships were fitted by nonlinear regression for all dolphinfish, female dolphinfish, male dolphinfish, and all wahoo sexes pooled. W-L relationships for monthly samples of female dolphinfish, male dolphinfish, and all wahoo with sexes pooled were also fitted by nonlinear regression. Predicted mean weight at length for wahoo was highest at the beginning of the spawning season in June and lowest after the spawning season in September. Maximum and minimum predicted mean weight at length for both sexes of dolphinfish did not correspond with the peak spawning period (March–May). Plausible migration models in conjunction with reproductive behavior were examined to explain the variability in monthly predicted mean weight at length for dolphinfish.

The 1996 U.S. Purse Seine Fishery for Tropical Tunas in the Central-Western Pacific Ocean

The U.S. tropical tuna purse seine fleet has fished the central-western Pacific Ocean under the South Pacific Tuna Treaty since 1988. The 1996 fishery was the poorest since the start ofthe Treaty. Fishing effort declined due to the financial collapse of a large fishing enterprise. Catches reached record lows for yellowfin tuna, Thunnus albacares, and skipjack tuna, Katsuwonus pelamis, and continued a declining trend that started in 1995. Catch rates also decreased to the lowest levels since 1991. Whether this declining trend in catch rates is due to reduced availability of fish caused by cyclic ocean environmental changes affecting vulnerability or to reduced abundance from excessive fishing pressure is not yet known and needs to be assessed.

Travel Characteristics of Marine Anglers Using Oil and Gas Platforms in the Central Gulf of Mexico

This study was designed to evaluate the travel characteristics of avid marine anglers off Louisiana in the Central Gulf of Mexico. It focuses on the complex marine travel patterns involving the extensive assemblage of oil and gas structures. In an intercept approach, marine recreationalf isherman were asked to identify near and offshore travel patterns on the day of the interview. Information was also solicited regarding how respondents selected and located fishing destinations as well as what method of fishing was undertaken that day. Petroleum platforms were a principal fishing destination, and platform anglers traveled an average distance of 75.5 km (40.7 n.mi.) to and from offshore fishing locations. In fishing an average of 6.5 platforms per trip, these anglers traveled about 21.3 km (11.5 n.mi.) between the first and last platform visited. Mean total distances for platform anglers were 96 km (51.8 n.mi). Travel distances for bay, nearshore, and bluewater anglers were also obtained.

Distribution and Apparent Abundance of the Basking Shark, Cetorhinus maximus, off the Central and Southern California Coast, 1962-85

Basking sharks, Cetorhinus maximus, are frequently observed along the central and northwestern southern California coast during the winter and spring months. These large plankton feeding elasmobranchs, second in size only to the whale shark, Rhineodon typus, had been the subject of a small commercial fishery off California in the late 1940's and early 1950's for their liver oil, rich in vitamin A, and in later years for reduction into fish meal and oil (Roedel and Ripley, 1950). These fisheries were sporadic and did not take basking sharks in large numbers.

Central Area Fisheries Advisory Committee 8th January, 1981

This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 8th January, 1981. It covers information on the review of fisheries byelaws, netting off Flimby beach, a large fish mortality in the River Calder and Ribble, and the review of a net limitation order which was due to expire. It also includes the stocking of Worthington Lakes, Rivington Group Reservoirs and the River Wyre, the update on the proposals for the development of angling at Stocks Reservoir and the report by the area fisheries officer on fisheries activities. This comments on river conditions and fishing for salmon, sea trout and brown trout, and migratory fish movement. Also covered in the report is an update on Middleton Hatchery, salmon cages in the River Leven, Langcliffe Hatchery and the pilot hatchery, and stocking numbers of coarse fish and non migratory trout by the Angling Associations. Finally the report adds about fish mortalities, fish disease, poaching and management work. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

Central Area Fisheries Advisory Committee 1st April, 1981

This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 1st April, 1981. It covers information on Rivers Leven and Kent fish distribution and water quality surveys 1980, authority works on Headwater Beck of the River Hodder and the River Douglas, the annual report on match fishing at Skerton and Mitton fisheries and the report by the area fisheries officer on fisheries activities. This comments on river conditions and fishing, migratory fish movement,an update on Middleton hatchery, salmon cages in Dalton-in-Furness, and Langcliffe hatchery. Finally the report adds about stockings by the authority, fish mortalities, fish disease and the monthy catches of salmon and sea trout for the 1980 season. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

Central Area Fisheries Advisory Committee 7th September, 1981

This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 7th September, 1981. It covers information including the consultation paper on the review of Inland and Coastal fisheries in England and Wales, a paper on 'A National Salmon Policy' and information on the response to an application for a professional eel trapper to fish for eels with fyke nets on Lake Windermere. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

Central Area Fisheries Advisory Committee 14th October, 1981

This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 14th October, 1981. It includes the information on the recommendations of the Area Fisheries Advisory Committees on the Review of Inland and Coastal Fisheries in England and Wales, and the restructuring of rod and line fishing licence duties. It also covers concern of the timing of recent repair work and a proposal for a fish trap on Forge Weir on the River Lune, and the report by the area fisheries officer on fisheries activities. This comments on river conditions and fishing, migratory fish movements, and an update on Middleton hatchery, Salmon Cages in the Leven, and Langcliffe hatchery. Finally the report adds about stockings carried out by the Authority, fish disease, fish mortality and management work. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

Central & Southern Area Fisheries Advisory Committee 18th January, 1982

This is the report from the Central and Southern Area Fisheries Advisory Committee meeting, which was held on the 18th January, 1982. It includes information on the restructuring of rod and line fishing licence duties, proposed introduction of fishery improvement grant and fishery equipment loan, schemes in 1983. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

Central Area Fisheries Advisory Committee 31st March, 1982

This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 31st March, 1982. It includes information on the River Leven smolt rearing scheme, the annual report on match fishing at Skerton and Mitton fisheries, and the report by the area fisheries officer on fisheries activites from September 1981 to January 1982. The report covers information on river conditions and fishing, migratory fish movements, an update on the work at Middleton hatchery, Salmon cages on the Leven and Langcliffe hatchery. It also includes information on fish disease, fish mortalities, management work and monthly salmon and sea trout catches for rod, line, nets and fixed engines for the 1981 season. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.