tribution and abundance. In analysis of survey data, 

 these results are a first approximation of correction 

 factors that could be applied to aircraft and ship- 

 board observations to provide more accurate 

 estimates of harbor porpoise abundance, although 

 caution should be exercised because of variable 

 sighting conditions or animal behavior. 



Further work on survey methodology should 

 examine the effect of eye height, survey speed, and 

 meteorological conditions upon survey results. Gas- 

 kin (1977) has discussed sea state and cloud 

 coverage as factors in survey results, and Scott and 

 Gilbert (1982) have examined several variables 

 affecting aerial surveys, but the effects of glare on 

 shipboard surveys and observer variability merit 

 further attention. Also, the estimation by observers 

 of distances from sighted porpoise to survey vessel 

 needs clear definition for open-ocean surveys 

 (Eberhardt 1978). Nevertheless, if survey methods 

 similar to those described here are adhered to during 

 the course of a survey, the results reported here are 

 applicable, and useful in estimating porpoise abun- 

 dance more accurately. 



Acknowledgments 



We gratefully acknowledge the cooperation of 

 several groups of people in completing this work. D. 

 Gaskin, E. Nol, L. Rae, P. Watts, B. Braune, M. 

 Showell, A. Read, F. Mercier, and B. VanNess of the 

 Cetacean Research Group of the University of 

 Guelph assisted with aerial and ground station data 

 collection. S. Katona, S. Rommel, S. Savage, L. Dod- 

 son, S. Warner, M. Wessel, M. Kovach, A. Blacat, R. 

 Dagit, C. Briggs, J. Winchell, W. Turner, D. Colombo, 

 K. Falls, and C. L. Danton from College of the Atlan- 

 tic participated in the survey methodology experi- 

 ment. P. Turnbull and R. Reeves of the New England 

 Aquarium were primary aerial observers for the sur- 

 vey experiment and provided extensive logistical 

 support. Additional help was provided by G. Stone, 

 D. Emerson, M. Lau, M. Godfrey, S. Marsh, D. Burn, 

 and J. Polishook. Assistance in typing and proofing 

 this manuscript was provided by Eleanor Jensen and 

 J. Casey. This paper is a contribution from Harold E. 

 Edgerton Research Laboratory of the New 

 England Aquarium. 



Literature Cited 



Amundin, M., and B. Amundin. 



1974. On the bahaviour and study of the harbour porpoise, 

 Phocoena phocoena, in the wild. In G. Pilleri (editor), 

 Investigations on Cetacea, VoL V, p. 317-328. Hirna- 

 natomisches Institut der Universitat, Berne. 



Eberhardt, L. L. 



1978. Transect methods for population studies. J. Wildl. 

 Manage. 42:1-31. 

 Gaskin, D. E. 



1977. Harbourporpoise/ J /7oco(Viap/jocoena(L.) in the western 

 approaches to the Bay of Fundy 1969-75. Rep. Int. Whal- 

 ing Coram. 27:487-492. 

 Gaskin, D. E., P. W. Arnold, and B. A. Blair. 



1974. Phocoena phocoena. Mamm. Species 42:1-8. 

 PRESCOTT, J., AND P. FlORELLI. 



1980. Review of the harbor porpoise {Phocoena phocoena) in 

 the U.S. Northwest Atlantic. U.S. Dep. Commer., NTIS 

 PB-80-176928. 

 Scott, G., and J. Gilbert. 



1982. Problems and progress in the U.S. BLM-sponsored 

 CETAP surveys. Rep. Int Whaling Comm. 32:587-600. 



The New England Aquarium 

 Central Wharf 

 Boston, MA 021 10 



School of Forest Resources 

 University of Maine 

 Orono, ME 04469 



The New England Aquarium 

 Central Wharf 

 Boston, MA 021 10 



SCOTTD. KRAI': 



James R. Gilbert 



John H. Prescott 



TOLERANCE OF FIVE-DAY-OLD WINTER 



FLOUNDER, PSEUDOPLEURONECTES 



AMERICANUS, LARVAE TO THERMAL 



SHOCK 1 



The winter founder, Pseudopleuronectes americanus 

 (Walbaum), is an important commercial and rec- 

 reational fish generally found in waters with tem- 

 peratures of 0° to 25 °C and salinities of 4 to 30 %o 

 (Pearcy 1962). The winter flounder ranges from 

 northern Labrador to Georgia, but is most commonly 

 found from the Strait of Belle Isle, northern shore of 

 the Gulf of St. Lawrence, to Chesapeake Bay. A 

 separate spawning population, or race, is found on 

 Georges Bank (Bigelow and Schroeder 1953). Smith 

 et al. (1975) indicated that there is a progression in 

 spawning time from south to north initiated by 

 increasing water temperature. Spawning generally 

 occurs in estuaries and shoal waters in winter and 

 early spring (Bigelow and Schroeder 1953) at tem- 

 peratures of 3° to 10°C and salinities of 15 to 35%o 

 (Rogers 1976). 



'Contribution No. 345, Marine Sciences Research Center, State 

 University of New York, Stony Brook, NY 1 1794. 



FISHERY BULLETIN: VOL. 81. NO. 4, 1983. 



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