at the end of 1964 will provide information on 

 growth, length of larval life, and period of 

 transformation to the parasitic phase. 



Fisheries and Limnology 



Two of the most serious gaps in the re- 

 search program were partially filled by the 

 establishment of Biological Stations on Lakes 

 Erie and Superior. No work of consequence 

 had been carried out on Lake Erie since 1930 

 although the commercial landings at selected 

 ports had been sampled each fall, beginning 

 in 1943. The Lake Superior fisheries received 

 some attention in 1950-52, but the reassign- 

 ment of the staff of the Biological Station at 

 Marquette to sea lamprey control forced re- 

 duction of the fishery work to annual sampling 

 of the spawning run of lake herring at major 

 ports and limited observations on the lake trout 

 fishery. 



The Lake Erie staff at Sandusky was con- 

 fronted with complex and difficult problems. 

 The fishery was well advanced in the decline 

 that was to carry two of the major "money" 

 fish, blue pike and whitefish, to the verge of 

 extinction and reduce the take of a third, the 

 walleye, to a small fraction of its former 

 level. A feature of the deteriorating fishery 

 appeared to be erratic and violent fluctuations 

 of year classes. The cause or causes of the 

 declinations were unknown, but evidence was 

 strong that the rapidly increasing pollution 

 from donnestic and industrial wastes was 

 creating a more and more unfavorable habitat. 

 It was necessary, therefore, to give close 

 attention both to the Lake and to the various 

 species of fish that live in it. 



To help the Sandusky staff, the research 

 vessel Cisco was assigned to Lake Erie for a 

 lakewide survey in 1957 and a more intensive 

 study of the productive western end in 1958. 

 At the same time, the vessel Musky was trans- 

 ferred from Hammond Bay to Sandusky. The 

 two vessels, working together, completed a 

 reasonably sound preliminary study of fish 

 stocks and limnological conditions. 



Vessel problems plagued the Sandusky staff 

 at the end of the 1958 season, when the Musky 

 had to be stripped and the badly deteriorated 

 hull destroyed. A chartered trap net boat, the 

 George L. , gave far from adequate service in 

 1959 and most of 1960. Inthefallof 1960 a new 

 steel hull was purchased, engines and gear 

 from the former Musky were installed, and the 

 Musky II , a most satisfactory research vessel, 

 was put into service. 



The research on Lake Erie has followed 

 three main lines. Experimental fishing, mostly 

 by trawl in the western part, gives annual 

 measures of the abundance of fish- -especially 

 of the group; the trawling was designed to 

 give a basis for statistical judgment on the 

 reliability of the records as measures of rela- 

 tive abundance of individual species. A second 



project has been the continuation on a broader 

 and sounder basis of the sampling of com- 

 mercial landings that was in effect before 

 the Station was established. The third major 

 line of study (much of it in collaboration with 

 the Environmental Research Program) con- 

 cerns the environment of the Lake with par- 

 ticular reference to the ecological require- 

 ments of major species. Since the Green Bay 

 and Saginaw Bay projects terminated in 1964, 

 the staff at Sandusky has assumed responsi- 

 bility for the collection of data from the conn- 

 mercial fisheries of the two Bays. 



The staff at the new Lake Superior station 

 at Ashland, like the one at Sandusky, suffered 

 initially fronn the lack of a good research ves- 

 sel. The Siscowet , which was transferred from 

 Marquette, required extensive modifications 

 that were not completed until near the end of 

 the 1958 season. The reconstructed Siscowet 

 is a sound, seaworthy craft equipped for both 

 fishery and limnological research. Most work 

 of the Siscowet has been in the Apostle Islands 

 region, but annual cruises have been made to 

 the northern (Isle Royale and Canadian North 

 Shore) and central (Keweenaw Bay and the 

 Marquette area) regions. 



The fishery program on Lake Superior has 

 concentrated along three major lines- -re- 

 search on lake trout over a widefield, analysis 

 of comnnercial landings of major species, and 

 studies on composition and distribution of fish 

 populations and related limnological condi- 

 tions. 



Lake trout research includes both the study 

 of the commercial landings (coverage is now 

 almost complete) and investigations by the 

 Siscowet . Connmercially caught lake trout are 

 examined for size, age, maturity, food, inci- 

 dence of lamprey wounds and scars, and origin 

 (natural and hatchery). Work by the Siscowet 

 is concentrated on the early life history 

 (especially through the first 3 to 4 years): 

 abundance of native and hatchery- reared young; 

 movements, distribution, growth, and survival 

 of planted fingerlings. The Siscowet also ob- 

 tains records for larger fish and makes annual 

 checks of the abundance of adult lake trout on 

 spawning reefs. 



The sampling of other commercially landed 

 fish is directed principally at whitefish and 

 lake herring in areas of greatest production. 

 Annual changes and local differences of growth 

 and year-class composition are followed. 



The Siscowet collects limnological data and 

 materials routinely and to meet special needs; 

 limnological "index" stations are visited on 

 schedule. The Siscowet's experimental fishing 

 yields information and materials on the distri- 

 bution, abundance, movements. . . of a wide 

 variety of species. In 1959, the Siscowet's work 

 was supplemented by the Cisco's survey of 

 eastern Lake Superior, 



The return of the Cisco to Lake Michigan in 

 1960 made possible the resunnption of work on 



