Spawning-strategy-dependent diets in two North American populations of Atlantic salmon Salmo salar.

The diet of repeat-spawner Atlantic salmon Salmo salar was investigated using carbon and nitrogen stable-isotope values from the outer growth band of scales, which reflect the fish's consumption and growth during their most recent marine phase. Isotope values for S. salar displaying different spawning strategies were compared between and within the Miramichi and Nashwaak Rivers, New Brunswick, Canada and a Bayesian mixing model was used to infer dietary contributions from potential prey items. Significant differences in the stable-isotope values were found among spawning strategies and between rivers, indicating differences in diet and feeding area, consistent with hypotheses. Bayesian mixing model results inferred the main prey items consumed during marine feeding by S. salar to consist of hyperiid amphipods and capelin Mallotus villosus for repeat alternate spawners from both rivers, sandlance Ammodytes sp. for repeat consecutive spawners from the Miramichi River and amphipods for repeat consecutive spawners from the Nashwaak River. These results demonstrate the diversity of feeding tactics among S. salar spawning strategies from the same river and between populations from different rivers. Accounting for differences in prey availability and the subsequent impact on S. salar diet and spawner return rates (i.e., marine survival) will facilitate the application of ecosystem-based management practices, such as ensuring that fisheries for forage species do not indirectly adversely affect S. salar return rates.

[1]  M. Power,et al.  Assessing the diet of North American Atlantic salmon (Salmo salar L.) off the West Greenland coast using gut content and stable isotope analyses , 2017 .

[2]  D. Righton,et al.  Ocean migration of pop-up satellite archival tagged Atlantic salmon from the Miramichi River in Canada , 2017 .

[3]  R. Nygaard,et al.  Changing trophic structure and energy dynamics in the Northwest Atlantic: implications for Atlantic salmon feeding at West Greenland , 2015 .

[4]  M. Power,et al.  Assessing the use of different marine growth zones of adult Atlantic salmon scales for studying marine trophic ecology with stable isotope analysis , 2015 .

[5]  Richard Inger,et al.  Best practices for use of stable isotope mixing models in food-web studies , 2014 .

[6]  I. Fleming,et al.  Large pelagic predators could jeopardize the recovery of endangered Atlantic salmon , 2014 .

[7]  James A. Smith,et al.  To fit or not to fit: evaluating stable isotope mixing models using simulated mixing polygons , 2013 .

[8]  L LacroixGilles,et al.  Population-specific ranges of oceanic migration for adult Atlantic salmon (Salmo salar) documented using pop-up satellite archival tags , 2013 .

[9]  M. Page,et al.  Matching and mismatching stable isotope (δ13C and δ15N) ratios in fin and muscle tissue among fish species: a critical review , 2013 .

[10]  A. Moore,et al.  Stable isotopes reveal age-dependent trophic level and spatial segregation during adult marine feeding in populations of salmon , 2012 .

[11]  H. Benoît,et al.  Evidence for bottom–up trophic effects on return rates to a second spawning for Atlantic salmon (Salmo salar) from the Miramichi River, Canada , 2012 .

[12]  G. Chaput.  Overview of the status of Atlantic salmon (Salmo salar) in the North Atlantic and trends in marine mortality , 2012 .

[13]  G. Chaput,et al.  SALSEA North America: a pelagic ecosystem survey targeting Atlantic salmon in the Northwest Atlantic , 2012 .

[14]  M. Power,et al.  Characterizing the trophic position and shift in Atlantic salmon (Salmo salar) from freshwater to marine life-cycle phases using stable isotopes , 2012 .

[15]  K. A. Mork,et al.  Distribution and biological characteristics of Atlantic salmon (Salmo salar) at Greenland based on the analysis of historical tag recoveries , 2012 .

[16]  P. Grønkjær,et al.  Spatial variability of carbon (δ 13C) and nitrogen (δ 15N) stable isotope ratios in an Arctic marine food web , 2012 .

[17]  P. Bustamante,et al.  Revisiting the use of δ15N in meso-scale studies of marine food webs by considering spatio-temporal variations in stable isotopic signatures – The case of an open ecosystem: The Bay of Biscay (North-East Atlantic) , 2012 .

[18]  A. Jamie,et al.  A model for estimating mortality of Atlantic salmon, Salmo salar, between spawning events , 2011 .

[19]  M. Renkawitz,et al.  Feeding ecology of early marine phase Atlantic salmon Salmo salar post-smolts. , 2011, Journal of fish biology.

[20]  A. Bond,et al.  Recent Bayesian stable-isotope mixing models are highly sensitive to variation in discrimination factors. , 2011, Ecological applications : a publication of the Ecological Society of America.

[21]  Richard Inger,et al.  Source Partitioning Using Stable Isotopes: Coping with Too Much Variation , 2010, PloS one.

[22]  V. Braithwaite,et al.  Stable isotope analysis of marine feeding signatures of Atlantic salmon in the North Atlantic , 2010 .

[23]  A. Bundy,et al.  Seals, cod and forage fish: A comparative exploration of variations in the theme of stock collapse and ecosystem change in four Northwest Atlantic ecosystems , 2009 .

[24]  M. Power,et al.  A comparison of muscle- and scale-derived delta13C and delta15N across three life-history stages of Atlantic salmon, Salmo salar. , 2008, Rapid communications in mass spectrometry : RCM.

[25]  H. Benoît,et al.  Impacts of environmental change and direct and indirect harvesting effects on the dynamics of a marine fish community , 2008 .

[26]  C. T. Marshall,et al.  Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon , 2008 .

[27]  W. Bowen,et al.  Dimensions of diet segregation in grey seals Halichoerus grypus revealed through stable isotopes of carbon (δ13C) and nitrogen (δ15N) , 2007 .

[28]  A. Moore,et al.  Use of the Stable Isotope Composition of Fish Scales for Monitoring Aquatic Ecosystems , 2007 .

[29]  D. Post,et al.  Getting to the fat of the matter: models, methods and assumptions for dealing with lipids in stable isotope analyses , 2007, Oecologia.

[30]  Maija Länsman,et al.  Temporal variation in abundance, return rate and life histories of previously spawned Atlantic salmon in a large subarctic river , 2006 .

[31]  G. Rose,et al.  Stable isotope analysis of some representative fish and invertebrates of the Newfoundland and Labrador continental shelf food web , 2005 .

[32]  G. L. Lacroix,et al.  Distribution of Atlantic salmon (Salmo salar) postsmolts of different origins in the Bay of Fundy and Gulf of Maine and evaluation of factors affecting migration, growth, and survival , 2005 .

[33]  R. Fuller,et al.  Determining trophic niche width: a novel approach using stable isotope analysis , 2004 .

[34]  Jae S. Choi,et al.  Transition to an alternate state in a continental shelf ecosystem , 2004 .

[35]  Nina Jonsson,et al.  Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life histories , 2003 .

[36]  J. Rasmussen,et al.  Variation in δ15N and δ13C trophic fractionation: Implications for aquatic food web studies , 2001 .

[37]  K. Kovacs,et al.  Marine mammals and the community structure of the Estuary and Gulf of St Lawrence, Canada: evidence from stable isotope analysis , 2001 .

[38]  L. Hansen,et al.  Feeding habits of wild and escaped farmed Atlantic salmon, Salmo salar L., in the Northeast Atlantic , 2001 .

[39]  M. J. V. Zanden,et al.  Comparing trophic position of freshwater fish calculated using stable nitrogen isotope ratios (δ15N) and literature dietary data , 1997 .

[40]  J. Simon,et al.  Recent excursions of capelin (Mallotus villosus) to the Scotian Shelf and Flemish Cap during anomalous hydrographic conditions , 1996 .

[41]  Kevin D. Friedland,et al.  Marine survival of North American and European Atlantic salmon: effects of growth and environment , 1993 .

[42]  M. Coutui.  EARLY MARINE LIFE OF ATIANTIC SALMON, SALMO SALAR, POSTSMOLTS IN THE NORmERN GULF OF ST. LAWRENCE , 1988 .