Showing papers by "National Marine Fisheries Service published in 1990"

Conservation Genetics of Pacific Salmon I. Temporal Changes in Allele Frequency

Abstract: Recent reductions in the abundance of all Pacific salmon species (Oncorhynchus spp.), coupled with large increases in artificial productioq demand that careful attention be paid to genetic changes occurring in both wild and cultured populations. Analysis of electrophoretic data for chinook salmon (O. tshawytscha) from the Pacific coast of Oregon revealed substantial allele frequency changes over 24 years in hatchery, but not wild populations. Unfortunately, our understanding of the causes of this result is hampered by a lack of theoretical models designed for organisms with life history features like those of Pacific salmon. We used computer simulations to provide a context for understanding genetic changes observed in the hatchery populations. Simulation results indicated that annual fluctuations in population allele frequencies due to genetic drift can typically be expected to be several percent, with the absolute magnitude determined primarily by the effective number of spawners each year rather than the age structure. Changes over 10- to 25-year periods were only slightly greater than short-term changes (1–5 years). The magnitude of allele frequency change over time was different for juvenile and adult samples. The probability of a significant test statistic comparing allele frequencies in temporally spaced samples increased with the ratio of sample size to effective number of breeders per year. This is an important consideration for conservation biologists, who typically are concerned with populations of small effective size. Simulation results indicate that it is necessary to postulate unrealistically large selection coefficients to explain the genetic changes in the hatchery populations by natural selection. The changes observed are consistent with a pure drift model provided that the effective number of breeders was as small as about 25–50 per year. Analysis of brood stock information for the hatcheries indicates that the effective population number may indeed have been this low, although the number of returning adults was often much larger. This conclusion underlines the importance of monitoring the genetic consequences of the large-scale artificial propagation program involving Pacific salmon. Se han observado reducciones recientes en la abundancia de la especie de salmon del Pacifico (Onoorhynchus spp.). Estos cambios estan relacionados con el incremento de la produccion artificial; lo cual requiere que se preste atencion especial a los cambios geneticos que estan ocurriendo en las poblaciones silvestres y cultivadas de esta especie. Un analisis de los datos electroforeticos para el salmon chinook (O. tshawytsha) de la costa del Pacifico de Oregon revelo cambios substanciales en la frecuencia de ale-los durante un periodo de 2–4 anos en los criaderos, pero no en las poblaciones silvestres. Desafortunadamente, nuestro entendimiento de las causas de este resultado es limitado dado a la falta de modelos teoricos disenados para organismos con ciclos de vida semejantes a las del salmon del pacifico. Nosotros utilizamos la simulacion por computadoras para proporcionar un contexto para entender los cambios geneticos observados en las poblaciones del criadero. Los resultados de la simulacion indicaron que las fluctuaciones anuales en la frecuencia de alelos de la poblacion dado a la deriva genetica, se espere que sean de varios porcentages. La magnitud absoluta es determinada principal-mente por el numero efectivo de hembras reproductivas cada ano en vez de la estructura de edades. Cambios geneticos durante un periodo de 10 a 25 anos fueron ligeramente mayores que cambios a corto plazo (1–5 anos). La magnitud en los cambios en la frecuencia de alelos a traves del tiempo fue diferente para las muestras de juveniles y de adultos. La probabilidad de un significativo test estadistico comparando frecuencias de alelos en muestras espaciadus en el tiempo aumento con la relacion de tamano de la muestra a numero efectivo de reproductores por ano. Esta es unu consideracion importante para biologos de conservacion, a quienes tipicamente les concierne el tamano efectivo de poblaciones pequenas. Los resultados de la simulacion indican que es necesario postular coeficientes de seleccion irrealisticamente grandes para explicar los cambios geneticos en la poblacion reproductiva por seleccion natural. Los cambios observados son consistentes con un modelo puro de deriva provisto que el efectivo numero de reproductores fue tan pequeno como 25 – 50 por ano. El analisis de la informacion del linaje reproductiue para los criaderos indica que el efectivo numero poblacional en realidad pudo haber sido tan bajo, a pesar de que el numero de adultos devueltos fue con frecuencia mucho mas grande. Esta conclusion subraya la importancia de evaluar periodicamente las consecuencias geneticas de los programas de propagacion artificial a larga escala que in-volucran a1 salmon del Pacifico.

Conservation Genetics of Pacific Salmon. II. Effective Population Size and the Rate of Loss of Genetic Variability

Abstract: A simulation model for genetic change in Pacific salmon (Oncorhynchus spp.) populations is extended to examine the loss of genetic variability

Conservation Genetics of Pacific Salmon. III. Estimating Effective Population Size

Abstract: The temporal method for estimating the effective population number from the standardized variance of allele frequency change (F^) is evaluated for a model incorporating the unusual life history features of Pacific salmon (Oncorhynchus spp.). Computer simulations were used to establish the relationship between F^ and N b , the effective number of breeders per year

Age and growth of Lutjanus kasmira (Forskål) in Hawaiian waters

Abstract: T.L.=34.0 { l-eXp[-0.29(i+ 1.37)]} where T.L. is total length (cm) and r is age (years). SEM observations reveaied that the slowgrowth hyaline zones were composed of daily increments too small (0.448 pm) to be resolved optically. Thus. age estimates derived by numerically integrating otolith growth rate data obtained with a light microscope showed a negative bias, resulting in overesumation of growth rates. Parameter estimates obtained from three different types of length-frequency analysis were also unstable. This was due. at least in part, to differences in the size composition of fish sampled with different fishing gears and from different depths. The growth rate registered in Hawaii falls within the reported growth coefficients of lutjanids. whereas it is one of the highest in the Pacific and clearly higher than a deep-water lutjanid species growth in Hawaii. Probably. this high growth rate may have been enhanced by the relative lack of competitors in the depauperate Hawaiian marine fish community.

Demographic Consequences of Changed Pupping and Hauling Sites of the Hawaiian Monk Seal

Abstract: During the last 30 years, changes in the size of Hawaiian monk seal populations at sewral locations baw been associated with the amount and type of human distur- bance. Recreational beach activities caused monk seals to alter theirpupping and baulingpattm Survival ofpups in suboptimal habitats was low, leading to gradualpopulation declines. During the last decade at Kure Atoll, thepmcess has been reversed human disturbance on beaches bas decreased and traditional pupping and hauling sites haw been rees- tablisbed Subsequently, high survival rates of young seals, coupled with two successful enhancement programs for fe- malepups, haw led to dramatic changes in the age and sex composition of the population Based on these changes, the monk seal population at Kure Atoll soon should begin to increase. Appamntly small bebaoioral changes in such vital activities as feeding and reproduction can baw large demo- graphic cotlsequences Tbmfm, moniton'ng of endangered species should include data on habitat use and age and sex composition as well as estimates of abundance

Control of Muscle Softening and Protease‐Parasite Interactions in Arrowtooth Flounder Atheresthes stomias

Abstract: Distinct proteolytic activity was observed in the incubated muscle tissue of arrowtooth flounder. Absorbance measurements of the TCA filtrates indicated maximum proteolytic activity between 55°C and 60°C, and minimum activity below 40°C. Instron puncture tests of raw, baked, steamed, deep-fat fried and microwaved samples of arrowtooth demonstrated that rapid inactivation of the protease(s) by microwave cooking significantly improved textural properties. Myxosporean parasites tentatively classified as Kudoa thyrsitis were identified in all but one of the arrowtooth samples. However, no clear relationship between parasite density and textural deterioration of the cooked fillets was observed.

Diel cycles in microbial manganese oxidation and manganese redox speciation in coastal waters of the Bahama Islands

Abstract: We observed pronounced die1 cycles in formation rates of particulate Mn in coastal waters of the Bahama Islands. Specific rates during the day were ?h Glasby 1984; Kalhorn and Emerson 1984). These transitions largely control the partitioning of Mn between dissolved and particulate (or solid) phases in natural waters and sediments and thereby regulate the scavenging of Mn from the water columns of lakes, rivers, and oceans as well as its transfer from sediments back into overlying waters. Mn redox processes are important biologically since Mn is an essential nutrient for all organisms. They also provide important controls on the geochemistry of many trace metals (Cu, Co, Ni, Zn, Pb, Cd, Ba, and others) that preferentially adsorb to Mn oxides (Balistrieri and Murray 1986) and on the large number of reduced substances that are oxidized by Mn oxides (numerous organics, Stone and Morgan 1984; sulfides, Stumm and Morgan 1970, 198 1; and H,Oz, Broughton and Wentworth 1947; Acknowledgments This research was supported by ONR grant N-00

Recruitment of Juvenile Striped Bass in the Roanoke River, North Carolina, as Related to Reservoir Discharge

Abstract: A multiagency committee was established to examine potential effects of reservoir management and hydroelectric power activities in the lower Roanoke River, North Carolina, on downstream resources and their users. Striped bass Morone saxatilis was selected as a key species because of the extensive long-term data base on spawning activity and nursery utilization established in the late 1950s. Specifically, the juvenile abundance index (JAI) values for young-of-year striped bass in Albemarle Sound (1955–1987) were compared to preimpoundment (1912–1950) and post-impoundment (1955–1987) flows of the Roanoke River during the spawning season (1 March–30 June). Recruitment was best (JAI > 5.0) for years in which river flows were low to moderate (5,000–11,000 ft3/s) and was poor (JAI 5.0) most closely resembled preimpoundment...

Genetic approaches to the management of Pacific salmon.

Abstract: The complex problems involved in managing Pacific salmon (Oncorhynchus spp.) are largely a consequence of the unusual life history features of these species. The strong homing instinct leads to the formation of discrete, locally-adapted spawning populations, each of which has the potential to evolve as an independent evolutionary unit. It is important, therefore, that the genetic consequences of different management policies be carefully evaluated. If current management goals (e.g., doubling the abundance of anadromous salmonids in the Columbia River basin through increased hatchery production and supplementation of natural populations) are realized, genetic issues will assume even greater importance in the future. To date, however, genetic concerns have not been adequately incorporated into the management process. We identify three genetic approaches, primarily based on easily obtained electrophoretic data, that can provide valuable information on which to base management decisions: (1) Using th...

Quantitative determination of optimum sustainable population level

Abstract: Quantitative methods are reviewed and compared for determining whether a marine mammal population is at an optimum sustainable population (OSP) level, a management goal specified by the U.S. Marine Mammal Protection Act. Methods of OSP determination fall into two general types: those that require an estimate of a population’s maximum net productivity level (e.g., the backcalculation method) and those that do not (e.g., dynamic response analysis). The two types differ in the data they require and in whether they determine OSP with respect to present or historical cartying capaaty. Backdadation and dynamic response analyses are compared using data on the California gray whale (Erchn’chtius robustus). Marine mammal monitoring programs should be designed to detect trends in both the abundance of a population and its condition relative to carrying capacity, because both quantities are involved in the definition of OSP. The value of using both abundance and condition indices in an assessment is illustrated with data on the nonhern fur seal (Callorhinus minus).

Toxicity of trace metals to Acartia tonsa in the Elizabeth River and southern Chesapeake Bay

Abstract: Dissolved zinc and copper and free cupric ions were present at high concentrations in water from the Elizabeth River estuary (a polluted tributary of the southern Chesapeake Bay) when compared to values in nearby Hampton Roads and lower Chesapeake Bay. Zinc concentrations at three stations in the Elizabeth River ranged from 87 to 1550 nM compared to values of 3·1 to 16 nM at four stations in the southern Chesapeake Bay. Likewise, free cupric ion concentration ranged from 10−11·6 to 10−10·1 M at the Elizabeth River stations, but was appreciably lower (10−12·3 to 10−12·6 M) in samples from Hampton Roads and the lower bay. In bioassays conducted with the copepod Acartia tonsa, the survival of naupliar larvae was much lower in Elizabeth River samples, containing high levels of copper and zinc, than in samples from the Chesapeake Bay or Newport River estuary which contained much lower levels of these metals. Based on previous results in trace metal ion buffered media, measured free cupric ion concentrations and estimated free zinc ion concentrations appear to have been high enough in the Elizabeth River samples to account for at least some of the observed decrease in larval survival. Furthermore, the addition of chelators, EDTA and NTA, that complex and detoxify copper and zinc (as well as cadmium, nickel and lead) significantly increased larval survival in the Elizabeth River samples. These results strongly support the hypothesis that elevated levels of copper and zinc (and possibly other toxic trace metals) occur at sufficiently high concentrations in Elizabeth River water to adversely affect Acartia tonsa and other sensitive estuarine organisms.

Age and growth of king and Spanish mackerel larvae and juveniles from the Gulf of Mexico and U.S. South Atlantic Bight

Abstract: Sagittal otoliths from 50 king mackerel 2.9–13.0 mm SL and 72 Spanish mackerel 2.8–22.0 mm SL collected off the southeast U.S. were examined whole at 400 × using a compound microscope-video system. Otoliths of both species had visible, presumably daily, growth increments as well as finer subdaily increments. Otolith growth was directly proportional to growth in standard length for king (r2 = 0.91) and Spanish mackerel (r2 = 0.86). Spanish mackerel were estimated to be 3–15 d old with a mean absolute growth rate (SL/number of growth increments) and 95% confidence interval of 1.15 ± 0.07 mm · d−1. The least squares linear equation: SL = −1.30 + 1.31 (age in days), with r2 = 0.67 and p < 0.001, described the relationship between length and age. There was a significant positive relationship between absolute growth rate and fish length. King mackerel were estimated to be 3–15 d old with a mean absolute growth rate of 0.89 ± 0.06 mm d−1. The least squares linear equation: SL = 0.37 + 0.82 (age in days), with r2 = 0.77 and p < 0.001, best described the relationship between length and age. The relationship between growth rate and fish length was not significant. The growth rate of king mackerel was slightly higher for fish from the Mississippi River plume than from all other locations combined, while Spanish mackerel growth rates were not significantly different.

Variability of the Columbia River plume observed in visible and infrared satellite imagery

Abstract: Variability of the Columbia River plume in coastal waters off the northwestern United States, 1979-1985, was observed in sea surface temperature and phytoplankton pigment images derived from Advanced Very High Resolution Radiometer and Coastal Zone Colour Scanner data. The orientation, shape, intensity and relative temperature of the plume vary in response to coastal winds and wind-driven surface currents. From October to April, plume water is oriented northward along the coast. Following the spring transition in April or May, the plume is oriented southward, either adjacent to the coast or offshore. Transition between the winter and summer forms can be observed in the satellite imagery. Brief reversals of the prevailing seasonal winds cause rapid changes in the orientation and shape of the plume. Remote sensing of the Columbia River plume offers valuable information for oceanographic studies and fisheries management in the region. Derivation of an appropriate visible-infrared signature for plume waters and tracking of tidal pulses in the plume is suggested as a promising direction for future research.

Diet composition of larval Leiostomus xanthurus in and about the Mississippi River plume

Abstract: The diet of the larvae of the sciaenid fish Leiostomus xanthurus collected within the Mississippi River plume differs from that of larvae collected in adjacent Gulf of Mexico shelf waters. Larvae collected in plume water had eaten twice as many food organisms as had larvae collected in shelf waters. Larvae collected within the plume had eaten mostly small food organisms (tintinnids, copepod nauplii, pelecypod veligers and invertebrate eggs), whereas larvae collected in shelf waters had eaten mostly larger food items (copepodite and adult copepods). Differences in the abundance of food organisms in and differences in the photic environments of these water masses may account for the differences in diet.

Effect of Feeding Rate on Growth and Feed Conversion of Florida Red Tilapia Reared in Floating Marine Cages

Abstract: An experiment was conducted to investigate growth, survival and feed conversion of Florida red tilapia reared in floating cages in seawater under different feeding regimens. Twenty-four cages (1 m3) were anchored in a sea pass on Great Exuma, Bahamas, and each was stocked with 300 juvenile, monosex males (10 g mean weight). Growth was monitored every 14 days for 84 days. Fish were fed daily a floating pelletized diet (32% protein) at 4 programed rates representing 50, 70, 90, and 110% of the estimated satiation rate, ad libitum, and by demand feeders, with each treatment comprised of 4 replicate cages. Final mean weight was significantly lower for the 50% treatment (94.1 g) than for all other treatments (range = 121.8–155.7 g). Final mean biomass per cage ranged from 24.2 to 39.4 kg/m3, and survival ranged from 98.2 to 99.8%. Mean specific growth rate was significantly lower under the 50% programed feeding treatment (2.42%/day) than for all other treatments (range = 3.15–3.56%/day) while feed conversion ratios (dry weight/wet weight) were significantly lower under the 50% (1.57) and 70% (1.68) programed feeding treatments than under all other treatments (range = 1.98–2.26). Thus, maximum growth was achieved at feeding rates near satiation while feed conversion was improved at lower feeding rates. Under demand feeding, growth and feed conversion were not significantly different than those of the ad libitum, 100%, and 90% treatments.

Adenosine Triphosphate Catabolites as Flavor Compounds and Freshness Indicators in Pacific Cod (Gadus macrocephalus) and Pollock (Theragra chalcogramma)

Abstract: Postmortem formation of 5′-inosine monophosphate, inosine and hypoxanthine in Pacific cod and pollock fillets during chilled storage was monitored over a two week period. Accumulation of hypoxanthine in Pacific cod (Gadus macrocephalus) fillets proceeded more slowly than has been reported for Atlantic cod (Gadus morhua) but similar to North Sea cod (Gadus callarias L.). For both both cod and pollock, hypoxanthine was negatively correlated with flavor and desirability (p < 0.01), while both inosine and 5′-inosine monophosphate were positively correlated with overall desirability (p < 0.01).

Diets of Young King and Spanish Mackerel Off the Southeast United States

Abstract: The diet of larval and post-larval (n = 95 and 307), and juvenile (n = 489 and 508) king (Scomberomorus cava/fa) and Spanish mackerel (S. macu/atus) from the Gulf of Mexico and southeastern Atlantic coastal waters of the U.S. consisted principally of fishes. Carangids, clupeids, and engraulids occurred in 23, 7 and 9% of larval and post-larval king mackerel stomachs and in 20, 40 and 7% of larval and post-larval Spanish mackerel stomachs, respectively. Sciaenids were also common in king mackerel, occurring in 21% of the stomachs. Prey fishes included the genera Cynoscion, Caranx, and Anchoa, and the species Opisthonema oglinum. Invertebrates, principally small crustaceans and nudibranch larvae, occurred infrequently in the diets of both species, but more so in Spanish mackerel than king mackerel. The dominant prey items for juvenile mackerels from the Atlantic were engraulids, clupeids, balistids, and squids, collectively accounting for 73.3% by volume of the diet of king mackerel and 88.8% of Spanish mackerel. More invertebrates occurred in the diet of juvenile Spanish mackerel than king mackerel, but they accounted for a smaller volume, i.e., 2.1% as compared to 5.4% for the Atlantic fish. Chi·square tests indicated significant differences between the diets of juvenile mackerel from the Gulf of Mexico and the Atlantic coast. [Kevwords: diets; king mackerel; Spanish mackerel] King mackerel (Scomberomorus Galveston Bay, Texas. Jenkins et a/. caval/a) and Spanish mackerel (S. macul(1984) studied the food habits of three atus) are widely distributed throughout species of Scomberomorus larvae from the western Atlantic and the Gulf of Mexthe waters off the Great Barrier Reef in ico. King mackerel occur from the Gulf Australia. Hunter and Kimbrell (1980) of Maine to Brazil, while Spanish macbriefly described the foods of Pacific kerel range from Cape Cod to Yucatan, mackerel, Scomber japonicus, and Last Mexico with centers of abundance off (1980) and Peterson and Ausubel (1984) Florida (Collette and Nauen 1983). Both presented the diet of Atlantic mackerel, species support important commercial Scomber scombrus, from the westand recreational fisheries in the southcentral North Sea and U.S. Middle Atlaneastern United States and Mexico. tic waters, respectively. The diet and feeding ecology of larKnowledge of the feeding ecology val and juvenile mackerels are poorly of young mackerels is necessary to known. Naughton and Saloman (1981) understand the role of diet and food reported on the stomach contents of availability in regulating growth, survival, juvenile king mackerel and Spanish macand ultimate recruitment. In addition, kerel from Cape Canaveral, Florida and knowledge of the diets of young king and 145 1 Finucane et al.: Diets of Young King and Spanish Mackerel Off the Southeast United Published by The Aquila Digital Community, 1990 146 Finucane, J.H., C.B. Grimes, and S.P. Naughton Spanish mackerel will be useful in understanding trophic interactions of mackerel and their associated species. In this paper we present the results of our diet studies on larval and juvenile king and Spanish mackerel from the Gulf of Mexico and southeastern Atlantic coastal waters of the U.S.

The New England Groundfish Fishery after 10 Years under the Magnuson Fishery Conservation and Management Act

Abstract: In the first 10 years under the Magnuson Fishery Conservation and Management Act, the New England and Mid-Atlantic regional fishery management councils (FMCS) managed 19 species of finfish and shellfish under eight fisheries management plans. The ability of the councils to effectively manage marine fisheries can be demonstrated by examining the management plans and levels of catch, and by noting the condition of the resource. Heavy foreign fishing during the 1960s and early 1970s was constrained by catch quotas imposed by the International Commission for Northwest Atlantic Fisheries, and the abundance of principal groundfish increased significantly by 1978. From 1976 to 1983, New England fishing effort doubled, and stocks that had not been heavily fished by foreign fleets went from being underfished to being overfished in just a few years. The total U.S. catch of finfish and squids steadily increased from 1973 to 1980 and then declined. The original Groundfish Plan was only for Atlantic cod Gadus...

Satellite-derived estimates of primary production on the northwest Atlantic continental shelf

Abstract: Synoptic estimation of rates of primary production from remote observation of ocean color is essential for determination of the ocean's role in global carbon cycles. Models having a physiological and optical basis have been developed to predict water-column primary production, normalized to water-column biomass, as a linear function of sea-surface irradiance. Such a model is applied using 41 successive images of sea-surface chlorophyll concentration derived from the Coastal Zone Color Scanner (CZCS) and covering the northeast coast of the U.S. and Canada in the spring of 1979. The CZCS level III data set for the northwest Atlantic continental shelf includes estimates of surface chlorophyll concentration and percent cloud cover on a 10 km grid. Linear regression techniques are used to calibrate the CZCS chlorophyll estimates with ship measurements and to convert percent cloud cover into sea-surface irradiance; such satellite-derived irradiance estimates are significant predictors of irradiances recorded at the earth's surface. The satellite-derived primary production values have been composited as monthly images. The enhanced production of the spring bloom is evident in areas corresponding to major fisheries such as Georges Bank and offshore Yarmouth, Nova Scotia, while the lower production in the Gulf Stream and an associated warm-core ring can be seen farther to the south. Bottom topography seems to have a major influence on rates of primary production, particularly in waters shallower than 100 m. The relative error estimated for these calculations of primary production is approximately 75%.

Patterns of nucleotide catabolism as freshness indicators in flatfish from the Gulf of Alaska.

Abstract: Hypoxanthine was the major catabolite of adenosine triphosphate (ATP) in rock, yellowfin, flathead and Dover soles examined from the Gulf of Alaska. Inosine monophosphate (IMP)/hypoxanthine (Hx) ratios were as effective as K1 values for assessing freshness. In contrast, inosine (HxR) was the end catabolite in rex sole and hypoxanthine was barely detectable. The gradual accumulation of hypoxanthine in rock and yellowfin soles made this catabolite a useful freshness indicator for these species.

Sex-specific DNA in reptiles with temperature sex determination.

Abstract: Banded krait minor ("Bkm") satellite DNA, originating in the W-chromosome of the snake Bungarus fasciatus, has been found in the genome of diverse eukaryotic species including fruit fly, quail, and horse. Concentrations of Bkm have been found in the presumptive W-chromosome of snakes with isomorphic sex chromosomes and in the male-determining region of the Y-chromosome in mouse and man. We therefore asked whether Bkm-related DNA might be present in quantitative excess in DNA from males or females in two related species of sea turtle, Chelonia mydas, in which sex is determined by the temperature of the incubating egg, and Lepidochelys kempi, in which the critical sex-determining temperature has recently been described. Filter hybridization with the Bkm 2(8) probe revealed male-specific fragments in both species; female-specific fragments were also revealed in C. mydas. Sex-specific DNA sequences in temperature-sex-determined species such as Kemp's ridley and the green turtle were unexpected, but could be explained if there were an underlying genetic mode of sex determination in these animals, or alternatively, if temperature-influenced sex determination involved structural modifications in DNA adjacent to, or directly concerned with, the sex-determining genes. If these results are confirmed across a broader sample of sea turtles, the techniques described in this paper might be used routinely to identify gener in the young of these endangered animals, in which male and female are grossly indistinguishable.