and physiology between reared and wild larvae 

 and concluded that results on growth, nutrition, 

 and mortality of laboratory-reared larvae should 

 not be related to the field. My study shows that 

 jack mackerel larvae reared with food in 10 1 

 containers were smaller and in poorer nutritional 

 condition than larvae reared in 100 1 containers. 

 These container-effects occurred at an early age, 

 i.e., morphological differences were evident 9 d 

 after hatching and histological differences 10 d 

 after hatching. Larvae may grow faster and show 

 fewer signs of starvation in large containers 

 because: 1) there is a lower probability of damage 

 from contact with the walls; and/or 2) the same 

 prey density in a larger container may permit the 

 formation of larger food patches and thereby 

 elevate the actual density of food encountered by 

 the larvae; and/or 3) water chemistry in larger 

 containers may be more favorable. 



In contrast to results of the feeding experiments, 

 larvae starved in 10 1 containers survived 2 d 

 longer and were larger at age 8 d than those in 

 100 I containers. This indicates that activity may 

 be affected by container size. Larvae in small 

 containers may be less active, consume energy 

 reserves less rapidly, and therefore live longer 

 without food. 



The effect of container size on growth, nutritive 

 condition, and possibly activity in jack mackerel 

 larvae, emphasizes the caution that must be 

 exercised when relating results from laboratory to 

 field conditions. The large container may have 

 had no effect on growth and development of jack 

 mackerel, but survival was poor. Further studies 

 are needed to determine the minimum container 

 size required to simulate natural conditions in the 

 laboratory. Because spatial requirements of larval 

 fish depend on locomotory patterns as well as on 

 genetic adaptations to life near solid surfaces 

 (Kinne 1977), optimum container size will prob- 

 ably vary with fish species. In larval fish experi- 

 ments, container size is a variable that must be 

 considered with temperature, light, food type and 

 availability, and stocking density. 



Acknowledgments 



Thanks to John Hunter and two anonymous 

 reviewers for critically reviewing the manuscript, 

 Jack Metoyer for helping me measure larvae, 

 Susan Picquelle for helping with the statistical 

 analyses, Kate Coleman for typing the draft and 

 tables, and Lorraine Prescott for final typing. 



Literature Cited 



AHLSTROM, E. H., AND O. R BALL. 



1954. Description of eggs and larvae of jack mackerel 

 {Trachurus symmetricus) and distribution and abun- 

 dance of larvae in 1950 and 1951. U.S. Fish Wildl. 

 Serv., Fish. Bull. 56:207-245. 

 BLAXTER, J. H.S. 



1976. Reared and wild fish — how do they compare? Proc. 

 10th Eur. Symp. Mar. Biol. 1:11-26. 

 Hunter, J. R. 



1976. Culture and growth of northern anchovy, Engraulis 

 mordax, larvae. Fish. Bull., U.S. 74:81-88. 



KLNNE, O, 



1977. Pisces: Rearing of larvae. In 0. Kinne (editor), 

 Marine ecology, Vol. 3, p. 968-1004. Wiley N.Y. 



Lasker, R., H. M. Feder, G. H. Theilacker, and R. C. May. 



1970. Feeding, growth, and survival of Engraulis mordax 

 larvae reared in the laboratory. Mar. Biol. (Lond.) 

 5:345-353. 



THEILACKER, G. H. 



1978. Effect of starvation on the histological and morpho- 

 logical characteristics of jack mackerel, Trachurus sym- 

 metricus, larvae. Fish. Bull., U.S. 76:403-414. 



1980. Changes in body measurements of larval northern 

 anchovy, Engraulis mordax, and other fishes due to 

 handling and preservation. Fish. Bull., U.S. 78:685-692. 

 Theil.acker, G. H., and M. E McMa.ster. 



1971. Mass culture of the rotifer Brachionus plicatilis and 

 its evaluation as a food for larval anchovies. Mar. Biol. 

 (Berl.) 10:183-188. 



Gail H. Theilacker 



Southwest Fisheries Center La Jolla Laboratory 

 National Marine Fisheries Service, NOAA 

 P.O. Box 271 

 La Jolla, CA 92038 



EFFECTIVENESS OF METERING WHEELS FOR 



MEASUREMENT OF AREA SAMPLED BY 



BEAM TRAWLS 



It was the purpose of this study to evaluate the 

 effectiveness of using an odometer wheel to mea- 

 sure distance sampled by a trawl. A 3 m beam 

 trawl has been used extensively in a series of 

 benthic ecology studies off the coast of Oregon at 

 depths ranging between 50 and 4,000 m. Two 

 odometer wheels were attached to the trawl in an 

 attempt to measure the distance covered during 

 sampling. The effectiveness of the odometers was 

 examined statistically from performance data col- 

 lected during 337 hauls over a 3,950 m depth 

 range. In spite of repeated use and repeated 

 suggestions as to the usefulness ( Holme and Mcln- 

 tyre 1971; Menzies et al. 1973) there have been no 



FISHERY BULLETIN: VOL. 78, NO. 3, 1980. 



791 



