Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine

Apollonio, Spencer and Stevenson, David K. and Dunton, Jr., Earl E. (1986) Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine. NOAA/National Marine Fisheries Service, (NOAA Technical Report NMFS, 42)

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Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near- surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night. Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C. An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.)

Item Type: Monograph or Serial Issue
Title: Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine
Personal Creator/Author:
Apollonio, Spencer
Stevenson, David K.
Dunton, Jr., Earl E.
Series Name: NOAA Technical Report NMFS
Number: 42
Date: 1986
Publisher: NOAA/National Marine Fisheries Service
Issuing Agency: United States National Marine Fisheries Service
Subjects: Ecology
Item ID: 2780
Depositing User: Patti M. Marraro
Date Deposited: 10 Nov 2009 12:29
Last Modified: 29 Sep 2011 18:27
URI: http://aquaticcommons.org/id/eprint/2780

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