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Use of Stable Isotopes to Identify Redds of Putative Hatchery and Wild Atlantic Salmon and Evaluate Their Spawning Habitat and Egg Thiamine Status in a Lake Ontario Tributary
Author(s) -
Fitzsimons John D.,
Dalton Alex,
MacVeigh Brydon,
Heaton Mark,
Wilson Chris,
Honeyfield Dale C.
Publication year - 2013
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1080/02755947.2013.806380
Subject(s) - salmo , hatchery , biology , fishery , tributary , habitat , ecology , fish <actinopterygii> , geography , cartography
Both wild and hatchery Atlantic Salmon Salmo salar can contribute to restoration but can exhibit differences in spawning habitat selection (e.g., water depth, current speed) and egg nutritional quality (e.g., thiamine), which affect reproductive success. Hence, there is a need to be able to differentiate the spawning contribution of the two groups in the wild. As diets of wild and hatchery‐reared spawners are markedly dissimilar and diet is known to influence stable isotope signature, egg stable isotope signatures offer the potential to discriminate redds of each. Using stable isotope analysis of carbon and nitrogen (δ 13 C and δ 15 N) of naturally spawned Atlantic Salmon eggs, we were able to discriminate the redds of putative wild (i.e., previously stocked life stage feeding in Lake Ontario; EWSR) from putative hatchery‐reared Atlantic Salmon (EHSR). Eggs of EWSR were significantly more enriched in nitrogen (δ 15 N: 15.0 ± 0.5‰ [mean ± SE]) but more depleted in carbon (δ 13 C: −26.6 ± 0.3‰) than eggs of EHSR (δ 15 N = 9.8 ± 0.6‰; δ 13 C = −17.5 ± 0.0‰). Eggs of EHSR were indistinguishable from eggs of known hatchery Atlantic Salmon for both δ 13 C and δ 15 N. Using stable isotopes to discriminate redd type, few differences were found between the spawning habitat of putative wild and hatchery spawners. Similarly using the same criteria, thiamine levels in eggs of EWSR (8,474 ± 840 pmol/g) were not significantly different from eggs of known wild Atlantic Salmon (3,691 ± 782 pmol/g) or of eggs of EHSR (14,865 ± 1,050 pmol/g), whose thiamine levels were indistinguishable from eggs of known hatchery Atlantic Salmon (14,200 ± 1,167 pmol/g). Egg thiamine levels for all groups were above established mortality thresholds. Our results indicate that both hatchery and wild Atlantic Salmon can make reproductive contributions, which can be differentiated and quantified using stable isotope signatures. Received August 24, 2012; accepted May 15, 2013