THE LIFE HISTORY AND TROPHIC RELATIONSHIP OF 

 THE NINESPINE STICKLEBACK, PUNGITIUS PUNGITWS, IN 

 THE APOSTLE ISLANDS AREA OF LAKE SUPERIORS 



Bernard L. Griswold^ and Lloyd L. Smith, Jr.^ 



ABSTRACT 



The ninespine stickleback is an important food of juvenile lake trout in the Apostle Islands 

 area. It is the most numerous fish of the area and is distributed in deep waters during the 

 winter and in shallow waters during the summer. Females grow faster than males, reaching 

 an average total length of 80 mm at age 5. Males live to age 3 and attain an average length 

 of 66 mm. Annulus formation on otoliths is complete by mid-July. Seasonal growth is more 

 than half complete by early August: growth of mature females -is delayed until after 

 spawning. 



Both sexes mature over a period of 3 yr. Spawning occurs from mid-June to late July. 

 Males apparently do not live as long as females, possibly because of a post-spawning mor- 

 tality. Egg number is a linear function of fish length, although this relationship is different 

 for fish from two separate areas. Environmental differences between these areas, which may 

 affect spawning time, possibly cause the differences in fecundity. Significant quantities of 

 maturing eggs atrophy just prior to spawning, a phenomenon which changes the fecundity 

 relationship. 



Sticklebacks eat a variety of invertebrates, particularly the crustaceans Mysis relicta and 

 Pontoporeia affinis. Food eaten by the stickleback and slimy sculpin is similar, but the 

 adaptability of both species tends to eliminate serious competition. The lake trout is the 

 only serious predator of stickleback. 



Investigations were made by the Bureau of 

 Commercial Fisheries (BCF) on the biology 

 of the fishes of Lake Superior from the early 

 1960's. These studies have been primarily life 

 history studies on economically valuable species 

 such as the lake trout. Salvelinus namaycush 

 (Walbaum). various coregonids, and the smelt, 

 Osmerus mordax (Mitchill). Some of the more 

 comprehensive of these include Bailey (1964), 

 Dryer (1963), and Dryer and Beil (1964). 



When it became apparent that these fish 

 stocks were being rapidly modified by exotic 

 species, particularly the sea lamprey, Pctro- 



' This work is a result of research sponsored in part 

 by the Minnesota Agricultural Experimental Station, 

 University of Minnesota, St. Paul, MN 55101. 



2 Northeast Fisheries Center, National Marine Fisheries 

 Service, NOAA, Woods Hole, MA 02543; present address: 

 Ohio Cooperative Fishery Unit, Department of Zoology, 

 Ohio State University, 1735 Neil Ave., Columbus, OH 

 43210. 



•* Department of Entomology, Fisheries and Wildlife, 

 University of Minnesota, St. Paul, MN 55101. 



myzon mariyius L., additional emphasis was 

 placed on ecological studies of noncommercial 

 fishes whose life histories are interrelated with 

 the exploited ones. One of these, the ninespine 

 stickleback, occurs in BCF index trawl samples 

 in greater numbers than any other. However, 

 prior to the study presented in this paper, its 

 ecological significance in these waters was 

 largely unknown. This study was designed to 

 investigate the life history of the ninespine 

 stickleback in the Apostle Islands region of 

 Lake Superior and determine the importance 

 of its relationships to the economically impor- 

 tant fish species of the area. 



The ninespine stickleback is one of the most 

 widely distributed northern fishes, occurring 

 in freshwater, estuarine, and coastal saltwater 

 environments (Bigelow and Schroeder, 1953). 

 It is abundant in cool-water habitats similar to 

 Lake Superior throughout the Northern Hem- 

 isphere. In middle western United States, it is 

 found in all the Great Lakes except Lake Erie 



Manuscript accepted March 1973. 



FISHERY BULLETIN: VOL. 71, NO. 4, 1973. 



1039 



