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Temperature-mediated growth dynamics of a gadoid, the Northeast Arctic saithe (1992-2013)

Sande, Hege (2015) BIOM01 20151
Degree Projects in Biology
Abstract
A relationship between climate and growth of fish has long been established for many marine species. To ensure sustainable management of fisheries resources, knowledge of key processes governing productivity, population size and individual growth is paramount. The Northeast Arctic saithe stock is found along the coast of Norway north of 62º N, and despite being an important gadoid of high ecological and commercial value, very little scientific attention has been allocated to the species, and attempts at establishing a relationships between climate and growth of NEA saithe have largely been unsuccessful. In this study the effect of climate on size and growth of NEA saithe was examined, using annual temperature anomaly at three coastal... (More)
A relationship between climate and growth of fish has long been established for many marine species. To ensure sustainable management of fisheries resources, knowledge of key processes governing productivity, population size and individual growth is paramount. The Northeast Arctic saithe stock is found along the coast of Norway north of 62º N, and despite being an important gadoid of high ecological and commercial value, very little scientific attention has been allocated to the species, and attempts at establishing a relationships between climate and growth of NEA saithe have largely been unsuccessful. In this study the effect of climate on size and growth of NEA saithe was examined, using annual temperature anomaly at three coastal stations as a proxy of climatic variability. Weight, length, Fulton K and specific growth rate of saithe age 2 and 3 were all found to be significantly affected by temperature anomaly, in addition to there being a geographical difference in the importance of temperature in the three regions examined presently. The results indicate that among the three regions, the southernmost (Bud) is probably the region where ambient temperature has been closest to optimum, while the largest proportion of variation explained by temperature was found for the northernmost regions (Eggum and Ingøy). Further studies are merited in this area, potentially aiding predictions on saithe growth and hence improve assessment and management of the NEA saithe stock. (Less)
Popular Abstract
How saithe respond to temperature changes along the Norwegian coast

To ensure sustainable management of fisheries resources, knowledge of key processes governing productivity, population size and individual growth are paramount. A relationship between climate and growth of fish has long been established for many marine species. Saithe is a marine demersal gadoid found in the northern Atlantic. The north-eastern stock has been separated into six stocks for management purposes, one of them being the northeast Arctic (NEA) saithe stock. NEA saithe is found along the coast of Norway north of 62° north, and is of great commercial and ecological value in the area. Saithe has been less well studied than other commercially exploited species,... (More)
How saithe respond to temperature changes along the Norwegian coast

To ensure sustainable management of fisheries resources, knowledge of key processes governing productivity, population size and individual growth are paramount. A relationship between climate and growth of fish has long been established for many marine species. Saithe is a marine demersal gadoid found in the northern Atlantic. The north-eastern stock has been separated into six stocks for management purposes, one of them being the northeast Arctic (NEA) saithe stock. NEA saithe is found along the coast of Norway north of 62° north, and is of great commercial and ecological value in the area. Saithe has been less well studied than other commercially exploited species, and very little is known about the mechanisms governing growth of saithe. In this study, I have investigated the variation in size and growth of NEA saithe in relation to temperature.

In order to do this, corresponding values of length, weight, condition (Fulton K) and specific growth rate were compared to temperature deviation from long term mean, focusing on age groups two and three. Saithe data used span the years from 1992 to 2013, and was provided by the Norwegian Institute of Marine Research (IMR), which has been carrying out annual acoustic surveys along the coast since 1985. This data was classified as belonging to one of three geographical regions along the Norwegian coast. In addition, data from cage reared saithe were included for comparison of growth rate under optimal condition (cage reared, full fed) and in the wild. Temperature was modelled for the three geographical regions along the coast (at a depth of 125 m), based on monthly means at fixed hydrographical stations (Ingøy, Eggum, and Bud). At each station, a mean was calculated from the years 1992-2013, and the yearly deviance from this mean was used in statistical analyses.

Results
Weight, length, Fulton K and specific growth rate of saithe age 2 and 3 were all found to be significantly affected by temperature variation, but there seems to be a geographical difference in the importance of temperature among the three regions examined presently. The results indicate that among the regions, the southernmost (Bud) is probably the region where ambient temperature has been closest to optimum, since this was where temperature variation explained the smallest proportion of growth and size variation. The largest proportion of variation explained by temperature was found for the northernmost region (Ingøy), indicating temperature here to be further from the optimum (Figure 1). As long as our knowledge about saithe is as limited with regards to factors driving growth, caution should be exercised when attempting predictions based on climate scenarios. However, as a relationship with the climate is indicated, further studies are merited in this area, potentially aiding predictions on saithe growth and hence, improve assessment and management of the NEA saithe stock.

Advisor: Anders Persson
Master´s Degree Project 30 credits in Aquatic ecology 2015
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Sande, Hege
supervisor
organization
course
BIOM01 20151
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
7440946
date added to LUP
2015-06-23 14:30:37
date last changed
2015-06-23 14:30:37
@misc{7440946,
  abstract     = {A relationship between climate and growth of fish has long been established for many marine species. To ensure sustainable management of fisheries resources, knowledge of key processes governing productivity, population size and individual growth is paramount. The Northeast Arctic saithe stock is found along the coast of Norway north of 62º N, and despite being an important gadoid of high ecological and commercial value, very little scientific attention has been allocated to the species, and attempts at establishing a relationships between climate and growth of NEA saithe have largely been unsuccessful. In this study the effect of climate on size and growth of NEA saithe was examined, using annual temperature anomaly at three coastal stations as a proxy of climatic variability. Weight, length, Fulton K and specific growth rate of saithe age 2 and 3 were all found to be significantly affected by temperature anomaly, in addition to there being a geographical difference in the importance of temperature in the three regions examined presently. The results indicate that among the three regions, the southernmost (Bud) is probably the region where ambient temperature has been closest to optimum, while the largest proportion of variation explained by temperature was found for the northernmost regions (Eggum and Ingøy). Further studies are merited in this area, potentially aiding predictions on saithe growth and hence improve assessment and management of the NEA saithe stock.},
  author       = {Sande, Hege},
  language     = {eng},
  note         = {Student Paper},
  title        = {Temperature-mediated growth dynamics of a gadoid, the Northeast Arctic saithe (1992-2013)},
  year         = {2015},
}