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Sea Temperature

Volume 410: debated on Friday 19 September 2003

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To ask the Secretary of State for Environment, Food and Rural Affairs what records she maintains of sea temperature around the various sectors of the British Isles; and what movements in temperature have taken place over the last 20 years. [130366]

Sea temperature data collected for the waters around the British Isles are collated by such national and international bodies as the British Oceanographic Data Centre and the Hydrographic Service of the International Council for the Exploration of the Sea (ICES).The ICES Working Group on Oceanic Hydrography produces an Annual Ocean Climate Status Summary of the North Atlantic Region, and include long time series from the seas around the British Isles.Other relevant publications include:

Alcock, G. and Rickards, L. (2001) Climate of UK waters at the millennium: Status and trends. Inter-Agency Committee on Marine Science and Technology, IACMST Information Document, 9, 48 pp.
Clark, R. A., Fox, C. J., Ben-Hamadou, R. and Planque, B. (2001) A directory of hydrographic and atmospheric datasets for the north east Atlantic and UK shelf seas. CEFAS, Science Series Technical Report, 113, 43 pp.

Round Britain most surface temperature series show a warming trend at a rate of between 0.5°C and 1°C per decade since the 1960s. This warming has largely been driven by a strongly positive phase of the fluctuating atmospheric pattern called the North Atlantic Oscillation (NAO).

To ask the Secretary of State for Environment, Food and Rural Affairs if she will list the sea temperature bands required by each main species of fish in waters surrounding the British Isles. [130367]

The table shows the estimated temperature range associated with several important commercial species:

Common nameScientific nameTemperature (°C) Range
CodGadus morhua0–20
HaddockMelanogrammus aeglefinus4–10
SaithePollachius virensTemperate
LingMolva molvaTemperate
WhitingMerlangius merlangusTemperate
MonkfishLophius piscatoriusTemperate
SalmonSalmo salar2–9
BassDicentrarchus labrax8–24
DogfishScyliorhinus CaniculaSub-tropical
PlaicePleuronectes platessa2–15
Lemon soleMicrostomus kittTemperate
SoleSolea solea8–24
HerringClupea harengus1–18
MackerelScomber scombrus4–14
SpratSprattus sprattusTemperate
PilchardSardina pilchardusSub-tropical


References to temperate and sub-tropical in the table indicate that a specified range is not available in the scientific literature.

While a change in sea temperature could affect stock distribution, spawning, migratory patterns and survival of very young fish, the effect of long term temperature trends on fish stocks is not easy to predict. Increased sea temperature has been linked to reduced recruitment (the numbers of young fish entering the population) in cold-water species such as cod, and improved recruitment in other species such as bass, but the factors influencing the survival of fish are complex and in many cases still poorly understood. For heavily fished species, fishing pressure remains the primary control on stock size but recruitment success also has a significant impact.