摘要:

Responses of a wild brook trout (Salvelinus fontinalis) population to instream habitat development in a 0.7 km reach of Lawrence Creek were monitored for 7 years and compared to population data for the 3-year period prior to development. Mean annual biomass of trout, mean annual number of trout over 15 cm (legal size), and annual production increased significantly during the 3 years following development, but more impressive responses were observed during the second 3 years. Maximum number and biomass and number of legal trout did not occur until 5 years after completion of development. The peak number of brook trout over 20 cm was reached the sixth year after development.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<361:ALEOTH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Experiments to evaluate mortality of age I+ hatchery-reared landlocked Atlantic salmon (Salmo salar) caused by hooking with four terminal gear types were conducted at the Cobb Fish-cultural Station, Enfield, Maine in fall, 1972–1974. For the 3 study years, there was an overall mortality of only 3.3% for 1,200 salmon caught by angling, and a mortality of only 0.3% for control fish. Of the total mortality of angled fish, 42.5% occurred within the first 24 hours. Worm-hooked salmon suffered significantly greater mortality (5.7%) than fish caught on all hardware (single- and treble-hook data combined) (P < 0.001) and by single-hook hardware only (P < 0.01). Fly-hooked salmon mortality (4.6%) was significantly greater (P < 0.01) than mortality of fish hooked on all hardware. There was no significant difference in mortality between worm-hooked and fly-hooked salmon. Mortality caused by hooking with worms was primarily from fish hooked in the eye (76%) and gill or gill arch (12%). Fly-caught mortalities had been hooked mainly in the isthmus or tongue (42%), esophagus or stomach (25%), and eye (25%).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<365:HMOLAS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Pound nets have frequently been blamed for the destruction of large quantities of undersized and immature fishes termed “scrap-fish,” which include commercially and recreationally important species. Capture of these small fishes is facilitated by the 51-mm stretched mesh size commonly used in the entrapment portion, or pound-head, of the net. Series of five major fish species in the scrap landings of the lower Chesapeake Bay were used to derive theoretical and experimental 50% retention lengths, plus gilling frequencies in experimental pound-heads with stretched mesh sizes ranging from 38 mm to 76 mm in 6.4-mm increments. Significant gilling in stretched mesh sizes of 57 mm and larger lead to the conclusion that 51-mm stretched mesh in pound-heads is a necessary though wasteful compromise. However, an escape panel of larger mesh size, located in the pound-head, would allow escapement of small sciaenids while retaining clupeids which are utilized as bait in the blue crab fishery. In situ mesh size measurements are necessary when determining selectivity characteristics of a particular pound-head.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<370:RAECOP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The Leslie matrix algorithm has been utilized to estimate mortality of a year class assuming an equilibrium population for a species. Under this assumption an estimate of the mortality for the 0thyear class of the Atlantic bluefin tuna (Thunnus thynnus thynnus) has been made indicating about five survivors from 10 million eggs in the first year of life. The mortality rates for later year classes were derived from empirical data.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<380:AMFDMR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Fecundity estimates were made on 428 mature herring (Clupea harengus harengus L.) (maturation stages 4 and 5) collected from the southern Gulf of St. Lawrence and the Nova Scotia coast. Estimates ranged from 23,000 to 261,000 eggs per female. Fecundity increased exponentially with the fish length and weight at different rates for different herring stocks. Values of the exponent ranged between 3.7–5.3 and 1.1–1.6 for length and weight, respectively. Results of regression analyses showed that fecundity depended more on fish weight and length than on age.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<384:FSOAHF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Seasonal depth distribution of landlocked alewives, Alosa pseudoharengus (Wilson), was determined in a shallow eutrophic lake. In spring they were concentrated in the deepest and coldest water, or less commonly near the warmer surface waters. During summer, alewives were evenly distributed above the anoxic hypolimnion. Their fall and winter actions were pelagic being characterized by avoidance of both surface and bottom waters.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<395:SDDOLA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Activity rhythms and light intensity preferences of largemouth (Micropterus salmoides) and smallmouth (M. dolomieui) black basses were investigated in laboratory experiments designed to elucidate aspects of niche separation between these sympatric congeners. Both species exhibited crepuscular activity, but M. salmoides also showed a mid-day activity peak. M. dolomieui avoided bright light, and their peak activity periods occurred at the beginning and end of the dark periods. Activity of M. salmoides was much more depressed during the dark periods, and rose sharply at the onset of light periods. Activity records in constant light conditions showed these activity rhythms to be endogenous.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<400:ARALIP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The growth of black crappie (Pomoxis nigromaculatus) and of white crappie (P. annularis) before a new forage fish, the Mississippi silverside (Menidia audens), became established in Clear Lake, California, was compared to their growth after the silverside had become established. Following the establishment of the silverside, growth rates of both species were slower than the presilverside growth rates for the first two years of life, and were apparently faster beyond year II. No correlation was found between changes in climatological conditions and crappie growth patterns. The overall impact of the silverside on the crappie fishery in Clear Lake may be negative if increased juvenile mortality rates result from the smaller sizes observed at the younger age classes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<404:EOTIOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Threadfin shad gizzard weights were used to determine the total length and total weight of threadfin shad. It was found that a high degree of correlation existed among the parameters tested and that the best relationship was between body weight to gizzard weight empty. Using this information it is possible to estimate the weights of threadfin shad eaten by predatory fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<409:UOGWTD>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

An analysis of age, growth, and fecundity was carried out on 208 quillback (Carpiodes cyprinus) and 32 highfin (C. velifer) carpsuckers collected from Four Mile Creek, Ohio, May-October, 1972. Back-calculations of growth indicated that C. cyprinus grows more rapidly than C. velifer, reaching its maximum size at age X. Males in both species were generally larger than females at each annulus, though the actual differences in length and weight were highly variable. The respective length-weight relationships for C. cyprinus and C. velifer were, respectively: log W = -4.06042 + 2.78559 log TL; and log W = -4.05206 + 2.80837 log TL; where W = wet weight (g) and TL = total length (mm). Monthly (May-October) condition coefficients for C. cyprinus ranged from 1.13 to 1.37 for males and 1.20 to 1.24 for females. Values for C. velifer (ages IV-VIII) ranged from 1.24 to 1.39.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<411:AGAFOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor