摘要:

Quantitative gravimetric analyses of stomach contents were carried out on juveniles of 21 species of fishes that cohabit seagrass beds near Crystal River, Florida. Our analyses were based on dry weights of food items and are expressed as percent of total stomach contents. The species analyzed were Harengula pensacolae, Opisthonema oglinum, Anchoa hepsetus, Anchoa mitchilli, Synodus foetens, Strongylura marina, Hyporhamphus unifasciatus, Oligoplites saurus, Trachinotus falcatus, Eucinostomus gula, Haemulon plumieri, Orthopristis chrysoptera, Bairdiella chrysura, Cynoscion nebulosus, Diplodus holbrooki, Lagodon rhomboides, Microgobius gulosus, Chasmodes saburrae, Menidia beryllina, Trinectes maculatus, and Sphoeroides nephelus. Analyses of stomach contents taken from small, sequentially arranged size classes enabled us to delineate discrete ontogenetic changes in food habits in many of the species. In the 15 species in which planktivorous feeding stages were detected, only zooplankters were consumed in measurable amounts. Juveniles of H. pensacolae, O. oglinum, A. hepsetus, A. mitchilli, and M. beryllina were almost exclusively planktivorous throughout most of the available size ranges and exhibited a distinct selection for molluscan veliger larvae. Copepods, mysids, and larval crustaceans were the principal plankters consumed by juveniles of other species. Only three species, D. holbrooki, L. rhomboides, and H. unifasciatus, exhibited herbivorous feeding stages. In both D. holbrooki and L. rhomboides, the herbivorous habit began quite early in juvenile development and followed a preliminary planktivorous stage. Larger specimens of L. rhomboides became carnivorous, whereas adults of D. holbrooki (and H. unifasciatus) were herbivorous. Juveniles of eight species exhibited carnivorous feeding stages, consuming primarily benthic invertebrates. Of these species, O. saurus, H. plumieri, O. chrysoptera, and B. chrysura consumed primarily shrimp and mysids; E. gula and T. maculatus utilized primarily polychaetes; C. saburrae consumed primarily amphipods; and T. falcatus consumed mainly crabs after utilizing mysids, small shrimp, and fishes in earlier feeding stages. In O. saurus, an intermediate stage was apparent in which material obtained from a cleaning habit made an important contribution to the diet. Juveniles of two species, L. rhomboides and C. nebulosus, exhibited carnivorous stages in which both benthic invertebrates and small fishes were important in the diet. Specimens of S. marina and S. foetens were primarily piscivorous. Detritus was an important dietary component in six species. In S. nephelus, M. gulosus, and C. saburrae, detritus was a major food item throughout most of the available size ranges. In M. beryllina, detritus was the major food item in the smallest size class examined. Appreciable amounts of detritus were also consumed by juveniles of O. oglinum and adults of H. unifasciatus.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<511:FHOJMF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Fifteen species of pelagic fishes were collected in 156 gill net sets at eight locations in the Sheepscot River-Back River estuary, Wiscasset, Maine, June 1970 through December 1971. Highest catches occurred June through August. Only the rainbow smelt is a year-round resident. Differences in abundance in space and time are apparently related to temperature. During the summer, alewives, blueback herring, and Atlantic menhaden were most abundant in the relatively warm Back River estuary, while Atlantic herring, Atlantic mackerel, and spiny dogfish were most abundant in the more oceanic Sheepscot River estuary. Prolonged near-freezing temperatures apparently limit the time pelagic fishes spend in the estuary and limit the number of species which can inhabit it. It is hypothesized that the distribution of pelagic species which exhibited preferences for colder water, such as Atlantic herring, would be most affected by artificial warming of the surface waters of the Back River estuary, if a new atomic powered generating plant were allowed to discharge heated effluent directly into it.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<541:DOPFIT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Twenty collections from 18 stations in Indian River and Rehoboth bays, June 1968 to April 1970, yielded 41,286 fishes representing 46 species. Five species, ecologically important as food for many local commercial species, comprised 89% of the total catch and were, in order of abundance: Fundulus majalis, Menidia menidia, Fundulus heteroclitus, Pseudopleuronectes americanus, and Anchoa mitchilli. Combined average biomass estimates for the five species were 55 kg/ha and 28 kg/ha for Rehoboth Bay in 1968 and 1969 respectively, and 76 kg/ha and 37 kg/ha for Indian River Bay in 1968 and 1969 respectively. Greatest species diversity and abundance occurred in summer, probably because this is when many of these species collected use these bays as nursery and feeding grounds. F. majalis, M. menidia, F. heteroclitus, P. americanus, Cyprinodon variegatus, and Syngnathus juscus apparently reside in these waters and spawn there during the spring and summer. Juveniles of many commercially important middle Atlantic species were also found in the bays during these seasons. P. americanus were the only fish available in any quantity to commercial and sport fisheries in the study areas. Other commercial fishes typical of the middle Atlantic region, such as Brevoortia tyrannus, Pomatomus saltatrix, and Paralichthys dentatus, were either scarce or occurred sporadically. Changes in species composition and numbers that have occurred in these bays during the past 12 years are probably the result of increased pollution and general environmental degradation.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<552:TFOTSZ>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Field experiments were conducted in the northeastern Gulf of Mexico off Panama City, Florida to evaluate the feasibility of using man-made midwater structures for attracting pelagic game fish to improve sportfishing catch rates. Significantly greater catches of little tunny (Euthynnus alletteratus), king mackerel (Scomberomorus cavalla), and dolphin (Coryphaena hippurus) were made around experimental structure sites than in adjacent control areas when equal experimental fishing effort was used.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<563:TEOMAS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A survey of sportfishing activity at the P. H. Robinson Generating Station discharge into Galveston Bay, Texas was taken from 21 October 1968 through 8 November 1969. During 108 daily checks, 1,063 fishermen were interviewed and 2,635 fish counted. Fishing activity was related to season and temperature of the heated effluent. Maximum fishing pressure and largest catches occurred during the period December 1968 through April 1969 and November 1969 when discharge water temperatures and flow rates were minimum. Lowest angling activity and catch rates were recorded from June through September 1969 when water temperatures approached 40 C in the upper part of the fishing area. Atlantic croaker, Micropogon undulatus; sea catfish (hardhead), Arius felis; sand seatrout, Cynoscion arenarius; black drum, Pogonias cromis; red drum, Sciaenops ocellata; and spot, Leiostomus xanthurus, in order of decreasing abundance, accounted for 96.7% of the fish counted during the study. Seine, trawl, and trammel net data taken from the outfall area indicated that creel survey data of fishing pressure and angling success were valid indicators of fish concentration.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<573:ACOSAA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Soluble proteins from the eye lens nucleus of bluefin tuna, Thunnus thynnus, were studied by electrophoresis. Polymorphism in proteins that migrated toward cathodal and anodal portions of the electropherograms is attributed to simple and complex genetic bases, respectively. Results suggest that bluefin in the California fishery belong to a single population which exhibits local genetic differentiation on the fishing grounds.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<578:APSBPF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Black drum were sampled from pound nets, haul seines, sport catches, and exploratory trawl and seine gear from 1959 through 1970 in a study of growth and distribution. Juveniles as small as 22 mm and adults up to 132 cm length and 46 kg (101.25 lbs) were examined. No sex differential in growth occurred and mean lengths for age-groups I, II and III were 223 mm, 406 mm and 562 mm respectively. Weights for the same age sequence are 0.17, 1.09 and 2.93 kg. More than one scale ring is apparently formed each year after the fourth year. Growth equations are: Ltin cm: 147.4 (1 - e-0.158(t + 0.04)), and Wtin kg = 52.9 (1 - e-0.160t)3. During the years 1962–1970, 69.6% of commercial landings by weight and 97.6% of citation sport catches by number occurred in the period April-June. Ocean surface temperatures at Chesapeake Light averaged 17.54 C with a standard deviation of 2.69 degrees coincidentally on days of sport catches April through June.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<584:AGADOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Horse mackerel, Trachurus murphyi, were collected during the fishing seasons of 1962–1963 and 1963–1964 from three different fishing areas off the coast of Chile. Age and growth were studied through the otoliths and length frequency distribution of the fish. More than 90% of the captures consisted of 4- to 6-year-old fish. The oldest specimen, measuring 63.5 cm and weighing 2,400 grams, was 10 years old. The major growth occurred during the first year of life.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<591:AAGOHM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A fin rot disease reached epizootic proportions in 1967 among at least 22 species of marine and euryhaline fishes in the New York Bight and has continued to occur annually to the present time. Fin necrosis was the consistent external sign of the disease; other external pathological changes included skin hemorrhages, skin ulcers and, occasionally, blindness. Bluefish, summer flounder, winter flounder, and weakfish were the principal species affected. Results of these studies indicate a bacterial cause. Bacteria of three genera, Aeromonas, Vibrio and Pseudomonas are likely implicated. Similar epizootics among freshwater fishes have been associated with unsanitary conditions in aquaria and with water pollution in nature. The epizootic primary center, lower New York Harbor, is grossly polluted with sewage and industrial wastes. We suspect pollution had a role in the disease.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<596:AFRDOM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The rate of oxygen consumption by organisms in pond waters, as measured by a dark bottle technique for a 24-hr period, increased with increasing chemical oxygen demand (COD). Rate of oxygen consumption increased with temperature between 15 and 35 C (Q10values were 1.5 to 2.0). At the same level of COD, oxygen consumption was greater in unaltered pond water than in water in which the plankton was heat-killed and oxygen was utilized only by bacteria and other decomposers. COD was positively correlated with increasing concentrations of chlorophyll in pond waters. The amount of COD in soluble organic matter ranged from 20.2 to 95.0% of the total COD. The percentage of the COD in the soluble fraction decreased with increasing quantities of phytoplankton. The average amounts of oxygen (mg oxygen/mg dry wt) required to completely oxidize various types of biological material were; phytoplankton from pure cultures 1.29, macroscopic algae 1.00, higher aquatic plants 0.99, particulate matter from pond waters 0.98, and fish 1.19.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<606:TCODOW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor