摘要:

When 171 sea lampreysPetromyzon marinuswere each offered a onetime choice of one large and two small lake troutSalvelinus namaycush, the ratio of their attacks (49.1%:27.5%: 23.4%) was similar to the ratio of host surface areas (51.4%:26.3%:22.3%) in laboratory tests conducted over 9 months in 1988–1989. When the smallest offered host was 560 mm total length (TL) or shorter, sea lampreys attacked the smallest host less often and the largest host more often than expected (N= 39) under assumptions that attacks would be either equal among the hosts (numbers-dependent hypothesis) or proportional to the hosts' surface areas (area-dependent hypothesis). When the smallest host was 615 mm TL or longer, observed attacks (N= 132) did not differ significantly from the number of attacks expected by either the numbers-dependent or the area-dependent hypothesis; however, the largest lake trout was almost always attacked more often than either of the smaller fish. These results are similar to field observations that sea lampreys kill few lake trout smaller than about 600 mm TL when larger fish are available as hosts, and that they attack larger fish (673–775+ mm TL) at a progressively greater rate as host size increases. Sea lamprey host-size selection was less pronounced in this study than in previous laboratory studies, which used smaller host fish than those now available in the Great Lakes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0637:HSBPSL>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

I used oxytetracycline to produce a time mark in the otoliths of stunted brook troutSalvelinus fontinaliscaptured in alpine lakes in the Sierra Nevada, California. Discernible annual features were present in otoliths ground to the sagittal midplane by means of a simple grinding technique. Age determinations made with cross sections were similar to those made with sagittal sections, suggesting that deposition continues on most surfaces of the otolith throughout the life of a stunted brook trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0644:AVAAMF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The trap fishery for Dungeness crabsCancer magisterin British Columbia is regulated by a minimum legal size limit of about 154 mm notch-to-notch carapace width (CW). This effectively bars females from the catch in most regional fisheries because few females attain this size. Consequently, in heavily exploited populations, males greater than the minimum legal size are rare and the sex ratio of adults favors females. As is typical of cancrid crabs, female Dungeness crabs mate with males considerably larger than themselves. In light of this and of data we present on male mating activity, sizes of mating pairs, and the degree of exploitation of males, we propose that females greater than about 140 mm CW would have difficulty finding a sexual partner in intensively exploited fisheries. Fewer matings of larger females could result in lost egg production, which suggests to us that increased understanding of the effects of a male-only fishery on the dynamics of Dungeness crab reproduction is important for confident management.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0650:NPCOIF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We maintained larvae of sea lampreysPetromyzon marinusand least brook lampreysLampetra aepypterafor I year at various proportions of the two species. Growth, measured as a change in length and weight, mortality, and incidence of metamorphosis were independent of species proportion in both species. Neither species was a superior competitor; interspecific competition appeared to act similarly to intraspecific competition.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0653:LSOGAI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Reproductive behavior has never been considered an important contributor to overall activity costs for fish and is usually ignored in fish bioenergetics models. We provide evidence that parental care by male smallmouth bassMicropterus dolomieusubstantially affects both activity costs and food intake. We used timelapse underwater video with infrared illumination to monitor nests of male smallmouth bass continuously for nearly 2 weeks from oviposition to swim-up of larvae, and we discovered that unlike nonnesting bass, nestguarding males were active during both night and day. Guarding males constantly sculled their caudal and pectoral fins (swimming in place) while on nests. We used caudal fin beat frequencies to relate the costs of swimming in place to those of nonguarding swimming. Combining these estimates with predictions of a respiration model for largemouth bassM. salmoides, we estimated that the metabolic rate of guarding smallmouth bass was up to 60% greater than that of nonguarding individuals. Energetic costs of nest guarding are exacerbated by food deprivation; the males we observed were unable to obtain appropriate daily rations while nesting. One of the guarding males disappeared prematurely under circumstances that suggested nest abandonment because of energetic constraints.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0657:IODANN>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

I used scuba and rotenone methods to determine the relative abundances offish in a cove at Beaver Reservoir, Arkansas. One day before rotenone was applied to a 1.2-hectare cove, divers swam nine transects to sample 944 m2. Divers observed 526 fish of nine species, whereas 8,700 fish of 21 species were documented with rotenone. There was a highly significant relationship (P< 0.001,r= 0.954) between the relative abundance of certain species of fish observed in scuba and rotenone samples. Significant correlations were also noted between size-classes of bassMicropterusspp. sampled by both methods.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0663:ACODAR>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Embryos and newly hatched larvae of Colorado squawfishPtychocheilus luciuswere immersed in tris-buffered solutions of 350 mg tetracycline hydrochloride (TC)/L of distilled water for 24 h (embryos) or 12 h (larvae). Larvae from both treatments were held indoors prior to swim-up and indoors or outdoors for 7 d after swim-up. Exposure to sunlight under simulated natural conditions had no detectable effect on quality or retention of fluorescent TC marks in otoliths. Marks in all otoliths examined were distinct and lucid to bright. Mark-recapture studies on age-0 Colorado squawfish could facilitate research needed for applied management and population recovery. Tetracycline marks in otoliths appear to be suitable for this purpose.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1991)120<0666:EOSOTM>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659-120.5.669

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor