Length-weight relationships of the anchoveta, Cetengraulis mysticetus, in the Gulf of Panama

ENGLISH: Knowledge of the length-frequency distribution and the length-weight relationships of the anchoveta is essential for converting the catch statistics of that species from pounds to numbers of fish. Such conversions are necessary for various types of investigations, especially those involving estimation of the population size and mortality rates. The analysis of the results of a recent tagging program conducted with anchovetas in the Gulf of Panama (Bayliff, 1965) requires that such conversions be made. Length-frequency data for the anchoveta have already been collected and published (Howard and Landa, 1958; Bayliff, 1964). The present report deals with length-weight data from fish collected in various .areas of the Gulf of Panama in all months of the year and in several different years. Opportunity is thus afforded to compare the length-weight relationships of fish of different year classes in different areas, months, and years. SPANISH: El conocimiento de la distribución de la frecuencia de longitud y de las relaciones entre la longitud y el peso de la anchoveta es esencial en las estadísticas de captura de esta especie para la conversión de peso en libras a número de peces. Estas conversiones son necesarias para varios tipos de investigación, especialmente las que se refieren a la estimación del tamaño de la población y de las tasas de mortalidad. Estas conversiones se requieren para analizar los resultados de un programa reciente de marcación de anchovetas en el Golfo de Panamá (Bayliff, 1965). Los datos de la frecuencia de longitud de la anchoveta ya han sido recolectados y publicados (Howard y Landa, 1958; Bayliff, 1964). El presente informe trata de los datos de longitud y peso de los peces recolectados en varias áreas del Golfo de Panamá durante todos los meses del año y durante varios años. Esto ofrece la oportunidad de comparar las relaciones entre la longitud y el peso de peces pertenecientes a varias clases anuales en áreas, meses y años diferentes.

A Photographic Catalog of Killer Whales, Orcinus orca, frOIll the Central Gulf of Alaska to the Southeastern Bering Sea

In 1992 and 1993, researchers from the National Marine Mammal Laboratory initiated photo-identification studies on Alaskan killer whales, Orcinus orca. Waters from Kodiak Island west to the central and eastern Aleutian Islands and southeastern Bering Sea were surveyed. A total of 289 individual whales were identified. A photographic record of the whales encountered during these surveys is presented. When photographs of the 289 individual whales were compared among various regions in Alaska (Prince William Sound and Southeast Alaska) and areas outside Alaska (British Columbia, Washington, and California), 11 matches were found. The count is conservative because the 1992 and 1993 surveys were limited in geographical range, restricted to summer periods, and whales may have been missed along the survey trackline. Future research incorporating both photoidentification studies and line transect surveys will provide reliable abundance estimates of Alaskan killer whales. (PDF file contains 58 pages.)

The History, Present Condition, and Future of the Molluscan Fisheries of North and Central American and Europe: Volume 1, Atlantic and Gulf Coasts

This three-volume monograph represents the first major attempt in over a century to provide, on regional bases, broad surveys of the history, present condition, and future of the important shellfisheries of North and Central America and Europe. It was about 100 years ago that Ernest Ingersoll wrote extensively about several molluscan fisheries of North America (1881, 1887) and about 100 years ago that Bashford Dean wrote comprehensively about methods of oyster culture in Europe (1893). Since those were published, several reports, books, and pamphlets have been written about the biology and management of individual species or groups ofclosely related mollusk species (Galtsoff, 1964; Korringa, 1976 a, b, c; Lutz, 1980; Manzi and Castagna, 1989; Shumway, 1991). However, nothing has been written during the past century that is comparable to the approach used by Ingersoll in describing the molluscan fisheries as they existed in his day in North America or, for that matter, in Europe. (PDF file contains 224 pages.)

Population Characteristics of Gulf Menhaden, Brevoortia patronus

The status of the gulf menhaden, Brevoortia patronus, fishery was assessed with purseseine landing data from 1946 to 1992 and port sampling data from 1964 to 1992. These data were analyzed to determine growth rates, biological reference points for fishing mortality from yield per recruit and maximum spawning potential analyses, spawner-recruit relationships, and maximum sustainable yield (MSY). Virtual population approaches were used to obtain point estimates of stock size, recruits to age I, spawning stock size, and fishing mortality rates. Exploitation rates ranged between 14% and 45% for age-1 fish, between 30% and 72% for age-2 fish, and between 36% and 71% for age-3 fish. Biological reference points from yield per recruit (FO. I: 0.7-0.9 yr-1) and maximum spawning potential (F20: 1.62.9 yr-l and F30: 1.0-2.1 yr-1) were obtained for comparison with recent estimates of F (0.4-0.8 yr-l). Parameters from Ricker-type spawner-recruit relations were estimated, although considerable unexplained variability remained. Estimates of long-term MSY from fits of the generalized production model ranged between 664,000 metric tons (t) and 897,000 t. Declines in landings since 1988 have raised concerns about the status of the gulf menhaden stock. However, gulf menhaden are short lived and highly fecund. Thus, variation in recruitment to age 1 largely mediated by environmental conditions influences fishing success over the next two years (as age-1 and age-2 fish). Comparisons of recent estimates of fishing mortality to biological reference points do not suggest overfishing. (PDF file contains 26 pages.)

Variability of Temperature and Salinity in the Middle Atlantic Bight and Gulf of Maine

Monitoring of the waters of the Middle Atlantic Bight and Gulf of Maine has been conducted by the MARMAP Ships of Opportunity Program since the early 1970's. Presented in this atlas are portrayals of the temporal and spatial patterns of surface and bottom temperature and surface salinity for these areas during the period 1978-1990. These patterns are shown in the form of time-space diagrams for single-year and multiyear (base period) time frames. Each base period figure shows thirteen-year (1978-1990) mean conditions, sample variance in the form of standard deviations of the measured values, and data locations. Each single-year figure displays annual conditions, sampling locations, and departures of annual conditions from the thirteen-year means, expressed as algebraic anomalies and standardized anomalies. (PDF file contains 112 pages.)

Early-life-history profiles, seasonal abundance, and distribution of four species of Clupeid larvae from the northern Gulf of Mexico, 1982 and 1983

We present data on ichthyoplankton distribution, abundance, and seasonality and supporting environmental information for four species of coastal pelagics from the family Clupeidae: round herring Etrumeus teres, scaled sardine Harengula jaguana, Atlantic thread herring Opisthonema oglinum, and Spanish sardine Sardinella aurita. Data are from 1982 and 1983 cruises across the northern Gulf of Mexico sponsored by the Southeastern Area Monitoring and Assessment Program (SEAMAP). This is the first such examination for these species on a multiyear and gulfwide scale. Bioproflles on reproductive biology, early life history, meristics, adult distribution, and fisheries characteristics are also presented for these species. During the summer, larval Atlantic thread herring and scaled and Spanish sardines were abundant on the inner shelf <40 m depth), but were rare or absent in deeper waters. Scaled sardine and thread herring were found virtually everywhere inner-shelf waters were sampled, but Spanish sardines were rare in the north-central Gulf. During 1982, larval Atlantic thread herring were the most abundant of the four target c1upeid species, whereas Spanish sardine were the most abundant during 1983. On the west Florida shelf, Spanish sardine dominated larval c1upeid populations both years. Scaled sardine larvae were the least abundant of the four species both years, but were still captured in 25% of inner-shelf bongo net collections. Round herring larvae, collected February-early June (primarily March-April), were abundant on the outer shelf (40-182 m depth) and especially off Louisiana. Over the 2-year period, outer-shelf mean abundance for round herring was 40.2 larvae/10 m2; inner-shelf mean abundances for scaled sardine, Atlantic thread herring, and Spanish sardine were 14.9, 39.2, and 41.9 larvae/l0 m2, respectively. (PDF file contains 66 pages.)

Benthic macrofauna and habitat monitoring on the Continental Shelf of the northeastern United States: I. Biomass

Information on long-term temporal variability of and trends in benthic community-structure variables, such as biomass, is needed to estimate the range of normal variability in comparison with the effects of environmental change or disturbance. Fishery resource distribution and population growth will be influenced by such variability. This study examines benthic macrofaunal biomass and related data collected annually between 1978 and 1985 at 27 sites on the continental shelf of the northwestern Atlantic, from North Carolina to the southern Gulf of Maine. The study was expanded at several sites with data from other studies collected at the same sites prior to 1978. Results indicate that although there was interannual and seasonal variability, as expected, biomass levels over the study period showed few clear trends. Sites exhibiting trends were either in pollution-stressed coastal areas or influenced by the population dynamics of one or a few species, especially echinoderms. (PDF file contains 34 pages.)

Results of abundance surveys of juvenile Atlantic and gulf Menhaden, Brevoortia tyrannus and B. patronus

The estuarine populations of juvenile Atlantic and gulf menhaden (Brevoortia tyrannus and B. patronus) were sampled during two-boat, surface-trawl, abundance surveys extensively conducted in the 1970s. Juvenile Atlantic menhaden were sampled in 39 estuarine streams along the U.S. Atlantic coast from northern Florida into Massachusetts. Juvenile gulf menhaden were sampled in 29 estuarine streams along the Gulf of Mexico from southeast Texas into western Florida. A stratified, two-stage, cluster sampling design was used. Annual estimates of relative juvenile abundance for each species of menhaden were obtained from catch-effort data from the surveys. There were no significant correlations, for either species, between the relative juvenile abundance estimates and fishery-dependent estimates of year-class strength. From 1972 to 1975, the relative abundance of juvenile Atlantic menhaden in north Atlantic estuaries decreased to near zero. (PDF file contains 22 pages.)

Gulf menhaden, Brevoortia patronus, Purse Seine Fishery, 1974-85, with a brief discussion of age and size composition of the landings

Routine biostatistical port sampling data and landings records collected from the gulf menhaden purse seine fishery between 1974 and 1985 are updated. During most of the period, a total of 11 menhaden reduction plants operated in Mississippi and Louisiana, and the number of vessels in the purse seine fleet varied from 71 to 82. Total annual landings ranged from 447,100 metric tons in 1977 to the record landings for the fishery of 982,800 metric tons in 1984. Age-I and -2 gulf menhaden annually comprised almost 96% of the landings. Estimated total numbers of menhaden landed varied from 4,510.5 million in 1975 to 11,154.9 million in 1985. Annual mean lengths and weights of sampled fish-at-age showed lillie variation. Nominal or observed fishing effort gradually increased through Ihe 1970s and 1980s, reaching 655,800 vessel-ton-weeks in 1983. (PDF file contains 14 pages.)

Stock assessment of the gulf menhaden, Brevoortia patronus, fishery

A stock assessment of the gulf menhaden. Brevoortia patronus, fishery was conducted with data on purse-seine landings from 1946 to 1985 and port sampling data from 1964 to 1985. These data were analyzed to determine growth rates, yield-per-recruit, spawner-recruit relationships, and maximum sustainable yield (MSY). Virtual population analysis was used to estimate stock size, year-class size, and fishing mortality rates. During the period studied, an average of 27% of age-l fish and 55% of age-2 and age-3 fish were taken by the fishery, and 54% for age-I and 38% for age-2 and -3 fish were lost annually to natural causes. Annual yield-per-recruit estimates ranged from 6.9 to 19.3 g, with recent mean conditions averaging 12.2 g since 1978. Surplus production models produced estimates of MSY from 620 to 700 kilometric tons. Recruits to age-I ranged from 8.3 to 41.8 billion fish for 1964-82. Although there was substantial scatter about the fitted curves, Ricker·type spawner-recruit relationships were found suitable for use in a population simulation model. Estimates of MSY from population simulation model runs ranged from 705 to 825 kilometric tons with F -multiples of the mean rate of fishing ranging from 1.0 to 1.5. Recent harvests in excess of the historical MSY may not be detrimental to the gulf menhaden stock. However, one should not expect long-term harvesting above the historical MSY because of the short life span of gulf menhaden and possible changes from currently favorable environmental conditions supporting high recruitment.(PDF file contains 24 pages.)

Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine

Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near- surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night. Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C. An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.)

Fishery atlas of the Northwestern Hawaiian Islands

This atlas summarizes data on the crustaceans, molluscs, and fishes caught in a resource survey of the Northwestern Hawaiian Islands from October 1976 to September 1981. The geographical and depth distributions, size range, and the type of gear used to catch all of the crustaceans, molluscs, and fishes are tabulated. Species accounts of 37 crustaceans, molluscs, and fishes of commercial potential are presented. The geography, oceanography, and climate of the region are reviewed. (PDF file contains 38 pages.)

Annotated bibliography on hypoxia and its effects on marine life, with emphasis on the Gulf of Mexico

This bibliography contains 73 annotated references from publications and reports concerning hypoxia, .,; 2.0 ppm dissolved oxygen concentration, in the Gulf of Mexico. Instances of hypoxia from similar habitats and the effects of low oxygen levels on marine or estuarine organisms are also included. (PDF file contains 15 pages.)

Net phytoplankton and zooplankton in the New York Bight, January 1976 to February 1978, with comments on the effects of wind, Gulf Stream eddies, and slope water intrusions

Results are given of monthly net phytoplankton and zooplankton sampling from a 10 m depth in shelf, slope, and Gulf Stream eddy water along a transect running southeastward from Ambrose Light, New York, in 1976, 1977, and early 1978. Plankton abundance and temperature at 10 m and sea surface salinity at each station are listed. The effects of atmospheric forcing and Gulf Stream eddies on plankton distribution and abundance arc discussed. The frequency of Gulf Stream eddy passage through the New York Bight corresponded with the frequency of tropical-subtropical net phytoplankton in the samples. Gulf Stream eddies injected tropical-subtropical zooplankton onto the shelf and removed shelfwater and its entrained zooplankton. Wind-induced offshore Ekman transport corresponded generally with the unusual timing of two net phytoplankton maxima. Midsummer net phytoplankton maxima were recorded following the passage of Hurricane Belle (August 1976) and a cold front (July 1977). Tropical-subtropical zooplankton which had been injected onto the outer shelf by Gulf Stream eddies were moved to the inner shelf by a wind-induced current moving up the Hudson Shelf Valley. (PDF file contains 47 pages.)

Observations on the taxonomy, biology, and ecology of the Engraulid and Clupeid fishes in the Gulf of Nicoya, Costa Rica.

ENGLISH: In 1952 and 1953, during the course of a study of the abrupt decline and apparent disappearance from the Gulf of Nicoya of the population of anchovetas (Cetengraulis mysticetus), an important tuna bait fish, considerable material was collected on the taxonomy, biology, and ecology of the several anchovies and the herrings inhabith1g the Gulf. The Gulf of Nicoya, approximately 50 miles long and varying in width from about 5 to 35 miles, is located on the Pacific coast of Costa Rica. The family Engraulididae is represented by four genera comprising fourteen species, and nine species were identified as members of eight genera of the family Clupeidae. All of the species inhabit other coastal areas of the tropical Eastern Pacific. SPANISH: En 1952 Y 1953, durante el curso de un estudio sobre la declinación abrupta y la aparente desaparición en el Golfo de Nicoya de la población de anchovetas (Cetengraulis mysticetus) un pez de importancia para la pesca del atún, se recolectó material considerable relacionado con la taxonomía, biología y ecología de las diversas especies de anchoas y arenques que habitan dicho Golfo. El Golfo de Nicoya, que mide aproximadamente 50 millas de largo y varía en su anchura entre 5 y 35 millas, se encuentra en la costa del Pacífico de Costa Rica. La familia de los Engráulidos está representada por cuatro géneros que comprenden catorce especies, y otras nueve fueron identificadas como miembros de ocho géneros de la familia Clupeidae. Todas estas especies habitan otras áreas costeras del Pacífico Oriental tropical. (PDF contains 144 pages.)