European sturgeon (Acipenser sturio L.) young of the year performance in different rearing environments –study within a stocking program

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

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Bycatch and landings of young of the year sharks in the Malaysian South China Sea: implications for conservation

Marine Biodiversity Records ◽

10.1017/s1755267215000561 ◽

2015 ◽

Vol 8 ◽

Author(s):

Azie Azri ◽

Takaomi Arai

Keyword(s):

South China Sea ◽

South China ◽

Fishing Gear ◽

Shark Species ◽

Vulnerable Species ◽

Critical Levels ◽

Sphyrna Lewini ◽

China Sea ◽

Young Of The Year ◽

Near Threatened

A total of 104 sharks were landed at fishing ports in the Malaysian South China Sea between 30 October and 24 December 2014, comprising the four families, Carcharhinidae, Hemiscylliidae, Sphyrnidae and Scyliorhinidae, and 11 of these shark species were examined. Measurements of size and weight were different and varied among species, ranging from 0.1 to 7.5 kg in body weight and from 31.1 to 105 cm in total length. Five of the 11 sharks,Carcharhinus sealei, Loxodon macrorhinus, Rhizoprionodon acutus, Hemigaleus microstomaandSphyrna lewini, were in the range of, or even less than, the lengths of those measured at birth in previous reports. The results suggest that these sharks were born just before they were landed.Sphyrna lewiniand H.microstomaare categorized as Endangered and Vulnerable species, respectively, and other sharks included in the landings are also categorized as Near Threatened. Thus, the current fishing methods could lead to critical levels of shark species in these waters, and even the future extinction of species. An improvement in the species selectiveness of fishing gear is needed to protect and conserve sharks in the area.

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Social influence on the correlation between behaviours in young-of-the-year perch

Behavioral Ecology and Sociobiology ◽

10.1007/s00265-006-0280-3 ◽

2006 ◽

Vol 61 (4) ◽

pp. 525-531 ◽

Cited By ~ 35

Author(s):

Carin Magnhagen

Keyword(s):

Social Influence ◽

Young Of The Year

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Wind-Aided Recruitment of Canadian Arctic Cisco (Coregonus autumnalis) into Alaskan Waters

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f88-110 ◽

1988 ◽

Vol 45 (5) ◽

pp. 906-910 ◽

Cited By ~ 10

Author(s):

Robert G. Fechhelm ◽

David B. Fissel

Keyword(s):

Time Series ◽

Canadian Arctic ◽

Wind Data ◽

Commercial Fishery ◽

Catch Per Unit Effort ◽

Longshore Currents ◽

Unit Effort ◽

Colville River ◽

Young Of The Year ◽

Mackenzie River

Summer wind data collected at Barter Island, Alaska, were compared with commercial fishery catches of arctic cisco (Coregonus autumnalis) at the Colville River, Alaska, for the period 1967–85. There was a significant (p = 0.036) association between yearly catch-per-unit-effort and the percent of easterly winds after adjusting for a 5-yr differential in the two time series. Results suggest that young-of-the-year fish which spawn in Canada's Mackenzie River are aided in their westward dispersal into Alaskan waters via wind-driven longshore currents. The greater the prevalence of easterly winds (westerly currents), the greater the recruitment. Increased recruitment manifests itself as an increase in Alaskan commercial fishery catch some 5-yr later when fish have grown to a size that renders them susceptible to commercial nets.

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Mechanisms underlying the increase in young-of-the-year Atlantic salmon (Salmo salar) density with habitat complexity

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f08-106 ◽

2008 ◽

Vol 65 (9) ◽

pp. 1956-1964 ◽

Cited By ~ 30

Author(s):

Oscar Venter ◽

James W.A. Grant ◽

Michelle V. Noël ◽

Jae-woo Kim

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Habitat Complexity ◽

Indirect Evidence ◽

Growth Potential ◽

Territory Size ◽

Complex Environments ◽

Atlantic Salmon Salmo Salar ◽

Direct Support ◽

Young Of The Year

We tested three hypotheses used to explain the increase in young-of-the-year (YOY) Atlantic salmon ( Salmo salar ) density with habitat complexity: the territory-size, predator-refuge, and foraging-benefits hypotheses. We manipulated habitat complexity in three different treatments (boulder-removed, control, and boulder-added) at eight sites in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick. The density of juvenile salmon was two times higher in the boulder-added treatment than in the other treatments. Our data were consistent with the territory-size hypothesis; visual isolation was highest and territory size was smallest in the boulder-added treatment, and salmon selected microhabitats to maximize their field of view. Our results showed partial support for the predator-refuge hypothesis; salmon in the boulder-added sites were closer to cover and showed a reduced reaction distance to a novel stimulus, but did not preferentially select microhabitats closer to cover. We found no direct support for the foraging-benefits hypothesis; however, there is indirect evidence that boulders may improve the growth potential of instream habitat. Our results suggest that YOY Atlantic salmon may be attracted to complex environments for the increased cover and that the decreased visibility of these sites causes a reduction in territory size, allowing a higher density of fish.

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