Showing papers by "National Marine Fisheries Service published in 1974"

Effect of Prey Distribution and Density on the Searching and Feeding Behaviour of Larval Anchovy Engraulis mordax Girard

Abstract: Laboratory estimates of the minimum concentration of food required for survival of marine fish larvae usually are much higher than the average concentrations of food in the sea (O’Connell and Raymond, 1970; Hunter, 1972). A common explanation for the fact that laboratory food requirements exceed natural food densities is that larvae are able to find and remain in patches of food in the sea which are considerably above the average food density estimated from plankton net catches. This explanation is supported in part by Ivlev (1961) who demonstrated with carp fry that an increase in the degree of aggregation of prey had the same effect on food consumed as an increase in the overall density of food material. A patchy distribution of larval food occurs under natural conditions. Thus, the effect of prey distribution on feeding behaviour of larval fish and the scale of “patchiness” of food items in the sea must be known to estimate the impact of food distribution on the feeding and searching behaviour of larval anchovy. This paper described some aspects of the effect of prey distribution and density on the feeding and searching behaviour of larval anchovy Engraulis mordax Girard.

Interconversion of Type C and D Strains of Clostridium botulinum by Specific Bacteriophages

Abstract: These studies show that Clostridium botulinum types C and D cultures can be cured of their prophages and converted to either type C or D depending on the specific phage used. Strains of types C and D were cured of their prophages and simultaneously ceased to produce their dominant toxins designated as C1 and D, respectively. Cured nontoxigenic cultures derived from type C strain 162 were sensitive to the phages from the toxigenic type C strain 162 and type D strain South African. When cured nontoxigenic cultures derived from strain 162 were infected with the tox+ phages from the 162 strain of type C and the South African strain of type D, they then produced toxin neutralized by types C and D antisera, respectively. Cured nontoxigenic cultures isolated from the type D South African strain were only sensitive to the parent phage, and, when reinfected with the tox+ phage, they produced toxin neutralized by type D antiserum. Type C strain 153 and type D strain 1873, when cured of their respective prophages, also ceased to produce toxins C1 and D, but, unlike strain 162 and the South African strain, they continued to produce a toxin designated as C2. When the cured cultures from strains 153 and 1873 were infected with the tox+ phage from type D strain 1873, the cultures simultaneously produced toxin that was neutralized by type D antiserum. When these cured cultures were infected with the tox+ phage from type C strain 153, the cultures produced toxin that was neutralized by type C antiserum. These studies with the four strains of C. botulinum confirm that the toxigenicity of types C and D strains requires the continued participation of tox+ phages. Evidence is presented that types C and D cultures may arise from a common nontoxigenic strain.

Identity and regulation of nutrients limiting phytoplankton production in the shallow estuaries near Beaufort, N.C.

Abstract: Inorganic nutrients limiting phytoplankton production in the shallow estuarine system near Beaufort, N. C., were identified by nutrient enrichment techniques. Nitrogen was the primary limiting nutrient; phosphorus also was limiting at times. Samples receiving a complete enrichment medium plus organic substrates poor or lacking in nitrogen and phosphorus showed no significant increase in relative photosynthesis over unenriched controls, even though there was a significant decrease in the nitrogen and phosphorus concentrations in the enriched samples. This suggested that microbial immobilization of nitrogen and phosphorus during decomposition of organic matter may limit nutrient availability to phytoplankton and in part account for the general paucity of inorganic nutrients present in this shallow system. An estimated 6 x 109 g carbon, 1 x 108 g nitrogen and 2 x 107 g phosphorus enters the estuarine system in the form of partially decayedSpartina alterniflora each year, primarily from September–March. To utilize the readily available fraction of this detrital material estuarine microbes would have to immobilize 2.4 x 107 g nitrogen and 1.6 x 106 g phosphorus. The data also suggested that an annual cycle in nutrient concentration in the estuarine system in part may result from shifts in the equilibrium between microbial immobilization and remineralization.

Biomass of Zooplankton in the Newport River Estuary and the Influence of Postlarval Fishes

Abstract: Numerical abundance, biomass, and caloric content of zooplankton were estimated from biweekly samples collected during 1970–1972 from the lower estuary of the Newport River, North Carolina. All three measurements generally were maximum during early fall and again in late winter or early spring. During November larval fishes, primarily pinfish (Lagodon rhomboides), spot (Leiostomus xanthurus), and menhaden (Brevoortia tyrannus), began entering the estuary. The larvae reached maximum abundance in the estuary during March and April. Zooplankton abundance declined significantly at this time during 1970 and somewhat later during 1971. We hypothesize that zooplankton abundance may control the survival of fishes during their transition from larvae to juveniles and that the larvae have a significant effect in reducing the standing crop of zooplankton. Analysis of the gut contents of these fishes indicated they feed predominantly on zooplankton. Routine metabolism of the larvae would require that the standing crop of larvae graze an average 10 percent of the 1970 standing crop of zooplankton daily during January–May.

Effects of benzene (a water-soluble component of crude oil) on eggs and larvae of pacific herring and northern anchovy

Abstract: The e f f e c t s of o i l s p i l l s on the marine environment have received increasing a t t en t ion over the pas t decade. A major port ion of the research on these e f f e c t s has followed a h o l i s t i c approach of subjecting organisms t o crude o i l . have contributed considerably t o an understanding of the problem, o i l i s a complex amalgam of severa l components, varying i n tox ic i ty . I t is d i f f i c u l t t o ascer ta in spec i f i c effects on the surv iva l and physiology of marine organisms using whole crude o i l . While some s tudies have focused on the e f f e c t of tar components i n o i l (Bargmann, 1971; Moulder and Varley, 1971), l i t t l e a t t en t ion has been given t o those compounds i n crude o i l thought most tox ic t o aquatic organisms, i .e. , the low boi l ing poin t , water-soluble, aromatic hydrocarbons. Although these s tud ies

The Diverse Patterns of Metamorphosis in Gonostomatid Fishes - An Aid to Classification

Abstract: The gonostomatid lightfishes rank second only to myctophid lantern-fishes in abundance in the sea. The gonostomatid genus Cyolothone has been singled out as the most abundant group of fishes in the ocean. These observations were based on abundance of adults in mid-water trawl hauls. If abundance is based on larvae, the gonostomatid genus Vinciguerria could be the most numerous group of fishes in the ocean. Without attempting to decide whether Cyolothone or Vinciguerria ranks first in abundance, we can assume that the gonostomatids obviously are an important group of oceanic fishes.

Comparison of a Natural Agglutinin in the Hemolymph of the Blue Crab, Callinectes sapidus, with Agglutinins of Other Invertebrates

Abstract: Cultivation of many invertebrates is of commercial value and an understanding of their immune mechanisms is important for combating the pernicious diseases that often debilitate them. Invertebrates possess a variety of humoral substances involved in internal defense that differ considerably from classical vertebrate antibodies (Bang, 1967; Carton, 1969; Feng, 1967; Sindermann, 1971; Tripp, 1970). Many of these hemolymph factors agglutinate a variety of foreign materials. Cantacuzene (1923) summarized his findings on invertebrate humoral substances including those capable of agglutination. Although his articles contain elaborate claims of results without adequate experimental data presented in protocol form, subsequent investigators are confirming many of these claims.

Feeding Habits of Young Winter Flounder (Pseudopleuronectes americanus): Prey Availability and Diversity

Abstract: The principal diet of age I+ winter flounder Pseudopleuronectes americanus captured in the Weweantic River Estuary, Wareham, Massachusetts was comprised of polychaetes, bivalves, gastropods, and crustaceans. During spring, flounder fed on planktonic crustaceans found within the estuary and during the summer and fall on mollusks and polychaetes at the estuary's mouth. A new technique, percent overlap, is described for the comparison of the volume percentages of food species in Peterson grabs and stomachs. Percent overlap values were progressively higher with each season: March, 1.8%; June, 29%; July, 47%; October, 47%. The low overlap values, occurring when fish were within the estuary, indicated that the benthic community was not an important food source. Diversity indices (Shannon-Weaver, Simpson and McIntosh) calculated for mollusks and macrocrustaceans were more variable at stations within the estuary than at the mouth.

Optically effective area of particle ensembles in the sea

Abstract: The optically effective area (OEA) concentration of particles was computed from measured size distributions and concentrations of particles in the upper 100 m of the Pacific Ocean off Baja California and is shown to correspond closely to direct measurements of the volume coefficient of light scattering at an angle of 20°, shown previously to be proportional to total scattering Plots of OEA as a function of particle diameter exhibit a maximum contribution at about 2 µm diameter at offshore stations and at 35 µm at nearshore stations The roll-off at smaller particle diameters is attributed to diminished optical efficiency rather than to decreased concentrations of smaller particles

A Radioisotopic Method of Measuring Food Evacuation Time in Fish

Abstract: Pinfish (Lagodon rhomboides) were fed cerium-144 labeled food to determine if movement of the label could be used to estimate food evacuation time. Radioactivity was retained by the fish until their gastrointestinal tracts were empty. Replicate measurements showed that individual fish may have significantly different evacuation rates. Cerium evacuation and serial slaughter methods provided similar estimates of evacuation time; for the same precision fewer fish are needed for the cerium method. From these experiments, it appears that 144Ce can be used as a tag to measure food evacuation time.

Summer Foods, Length-Weight Relationship, and Condition Factor of Juvenile Ladyfish, Elops saurus Linnaeus, from Louisiana Coastal Streams

Abstract: A total of 295 juvenile ladyfish Elops saurus Linnaeus were collected with surface trawls from Louisiana coastal streams in June 1968 and June 1969. The fish ranged from 45 to 201 mm in fork length. Of the 295 ladyfish stomachs examined, 229 (77.6%) contained food. Fish constituted 94.5% by occurrence of the food organisms and decapod crustaceans 5.5%. Gulf menhaden comprised 72.0% of the fish identified. The calculated length-weight relationship for juvenile ladyfish in the size range 45-201 mm (fork length) was log10W = −5.3295 + 3.1123 log10L, and the mean condition coefficient was 8.1.

Case reports of ossifying fibromata in the striped mullet.

Abstract: Ossifying fibromata are described from three striped mullet (Mugil cephalus) from the Gulf of Mexico near Galveston, Texas. The tumors were classified as ossifying fibromata based on their predominately fibrous composition, the presence of bone spicules in the larger tumors, and the absence of mitotic figures.

Bone particle content of some minced fish muscle products

Abstract: Minced fish muscle recovered by flesh separators may vary in bone particle content depending on the type of machine and the size of the openings that the fish are passed through to screen out the skin and bones. Orderly marketing of these materials will require some measure of control of the bone particle content. The method presented here for quantifying the bone particle content of minced flesh by gravity-flotation involves (1) shredding the flesh with a low-speed stirring device and (2) gravity separation of the bone, cartilage and other high-density components from the lower-density floatable muscle fibers. Experimental samples obtained by passing various fish materials through flesh separators and then through 1- and 2-mm flesh strainers were analyzed for their bone particle content by the proposed method. The bone particle content of flesh containing 25 to more than 100 particles per pound could be reduced by 70–100% by passage through strainers. Imported commercial samples displayed bone particle contents of 4 to over 400 per pound. Sensory panels could not detect more than 10% of the particles found by objective analysis. The gravity-flotation method may serve as a useful quality control tool.

Preliminary results of fisheries investigation associated with Skylab-3

Abstract: The author has identified the following significant results. This investigation is to establish the feasibility of utilizing remotely sensed data acquired from aircraft and satellite platforms to provide information concerning the distribution and abundance of oceanic gamefish. Data from the test area in the northeastern Gulf of Mexico has made possible the identification of fisheries significant environmental parameters for white marlin. Predictive models based on catch data and surface truth information have been developed and have demonstrated potential for reducing search significantly by identifying areas which have a high probability of being productive. Three of the parameters utilized by the model, chlorophyll-a, sea surface temperature, and turbidity have been inferred from aircraft sensor data. Cloud cover and delayed receipt have inhibited the use of Skylab data. The first step toward establishing the feasibility of utilizing remotely sensed data to assess amd monitor the distribution of ocean gamefish has been taken with the successful identification of fisheries significant oceanographic parameters and the demonstration of the capability of measuring most of these parameters remotely.