Production of Fish Stocks in Thingvallavatn, Iceland

Annual net production of four morphs of 1+ and older arctic charr Salvelinus alpinus (L.) and threespined stickleback Gasterosteus aculeatus L. in Thingvallavatn, Iceland, was estimated. Production of the dominant morph, planktivorous charr, was 28.3 KJ m-2 yr-1, which constitutes 14.3% and 0.8% of...

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Bibliographic Details
Published in:Oikos 1992-05, Vol.64 (1/2), p.371-380
Main Authors: Snorrason, Sigurdur S., Sandlund, Odd Terje, Jonsson, Bror
Format: Article
Language:English
Subjects:
Agnatha. Pisces
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Arithmetic mean
Biological and medical sciences
Biomass production
Demecology
Fishes
Freshwater
Freshwater fishes
Fundamental and applied biological sciences. Psychology
Gasterosteus aculeatus
Lakes
Littoral zones
Marine fishes
Primary productivity
Production estimates
Salvelinus alpinus
Streams
Trout
Vertebrata
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Summary:Annual net production of four morphs of 1+ and older arctic charr Salvelinus alpinus (L.) and threespined stickleback Gasterosteus aculeatus L. in Thingvallavatn, Iceland, was estimated. Production of the dominant morph, planktivorous charr, was 28.3 KJ m-2 yr-1, which constitutes 14.3% and 0.8% of the estimated zooplankton and phytoplankton production, respectively. Corresponding values for the benthic charr morphs, i.e. small and large benthivorous charr of the stony littoral zone (0-10 m depth), was 1.2 KJ m-2 yr-1, which amounts to 1.8% and 0.23% of the estimated secondary and primary production in this zone, respectively. Estimated production of the piscivorous morph, which primarily inhabits the benthic Nitella-zone (10-20 m depth) and feeds on sticklebacks, was 1.3 KJ m-2 yr-1. Production of the stickleback, which also lives in the Nitella-zone, was estimated at 2.2 KJ m-2 yr-1, which is 11.6% and 0.3% of the estimated secondary and primary (Nitella excluded) production in this zone, respectively. The piscivorous part of the piscivorous morph, i.e individuals larger than 230 mm in fork-length, produced 0.24 KJ m-2 yr-1, which is 11% of the stickleback production, but only 0.7% of the total production of fish which consume invertebrates in the lake. The total production of fish in the lake, 33 KJ m-2 yr-1, is high for a subarctic lake.
ISSN:0030-1299
1600-0706
DOI:10.2307/3545059