Do diet of long rough dab (Hippoglossoides platessoides) differ between fjords with and without red king crab (Paralithodes camtschaticus)? A study of summer diet
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https://hdl.handle.net/10037/11340Dato
2017-05-15Type
Master thesisMastergradsoppgave
Forfatter
Kiærbech, KristofferSammendrag
The purpose of this study is to describe the diet of long rough dab in three different fjords
with and without red king crab. The hypothesis is that red king crab are influencing the diet
and possible also growth of long rough dab. By the applying objectives it is assumed to give
an answer to if red king crab is influencing different aspects of the diet and growth in long
rough dab.
By the applied frequency of occurrence and weight % analyses there were found small
differences in the long rough dab diet. There was a dominance of different Crustacea and
some Polychaeta prey groups. The main differences between the fjords was high dominance
by fish, Bivalvia and Pandalidae in Porsanger, and little dominance of fish and Bivalvia prey
groups in Balsfjord. A diet shift with increased predator length were recognized in both
Balsfjord, Kvænangen and Porsanger long rough dab diet. The shift in Balsfjord were from a
Crustacea dominance to Polychaeta and Crustacea dominance. Kvænangen with the opposite
result. Porsanger having the most diverse diet in regard to prey groups contributing to the
energy budget. The diet shift is towards a more fish and Pandalidae dominated diet.
There were found small differences in growth in the three populations of long rough dab, with
Porsanger material being in slightly better condition. There is by this study not found
indication of an impact of red king crab on diet and growth in long rough dab. Though there is
assumed that the low size of the cod stock in Porsanger, might let the long rough dab to
include more fish and Pandalidae into their diet. This is relative high energetic prey which
might held the growth rate up in a situation where the ecosystem are in change. In a situation
with a large cod stock in a fjord area, there might possible be a larger influence of red king
crab on the diet and growth in a population of long rough dab.
Keywords: Long rough dab, Hippoglossoides platessoides, diet, growth, red king crab
influence.
Forlag
UiT Norges arktiske universitetUiT The Arctic University of Norway
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