Whole otolith elemental analysis reveals feeding migration patterns causing growth rate differences in anadromous whitefish from the Baltic Sea

• Impact of feeding migration pattern on growth rate of whitefish (Coregonus lavaretus L.) from River Kemijoki was investigated. River Kemijoki is located in the northernmost Gulf of Bothnia (Baltic Sea). Whitefish ascending the river to spawn show major growth rate variations. To study whether these variations are related to different feeding areas (migratory connectivity), whole otoliths from fast-growing (FAST(G)) whitefish (n=9, age 4years, average weight 790g) and slowly growing (SLOWLYG) whitefish (n=9, age 8years, average weight 600g) were analysed for elemental (Ba, Sr, Mg, Zn, Mn, Ca) concentrations by inductively coupled plasma-optical emission spectrometry. Results showed that the FAST(G) whitefish had much lower otolith Ba concentration (similar to 45%, p.01) than SLOWLYG whitefish, revealing that FAST(G) whitefish have spent more time in water of higher salinity/lower latitude, that is at feeding grounds in the southern Gulf of Bothnia. Otoliths of the FAST(G) whitefish had also higher Mg (similar to 25%, p.001) and Zn (similar to 20%, p.05) concentrations, but lower Ca (similar to 5%, p.01) concentrations, than the otoliths from SLOWLYG whitefish. These results further reveal that FAST(G) and SLOWLYG whitefish have been spatially separated. In conclusion, bulk otolith elemental analysis revealed spatial separation and migration differences in river-spawning whitefish subpopulations in the Gulf of Bothnia, which apparently lead to differences in fish growth rate. Our results increase the understanding of river-spawning whitefish biology and its population structure and dynamics and may contribute to a sustainable management of river-spawning whitefish stocks.

Ämnesord

LANTBRUKSVETENSKAPER  -- Annan lantbruksvetenskap -- Vilt- och fiskeförvaltning (hsv//swe)

AGRICULTURAL SCIENCES  -- Other Agricultural Sciences -- Fish and Wildlife Management (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

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