Publications

Growth was studied of five year classes of the northern brook lamprey, Ichthyomyzon fossor, collected from the Sturgeon River during intervals between treatment of the stream with a lampricide. Growth varied considerably among year classes. Larvae of the 1963 year class were slightly longer at age II and 30% longer at age III than the III-group larvae of the 1960 year class. About 6% of...

Eggs from Lake Michigan alewives (Alosa pseudoharengus) were incubated at 79 different temperatures from 42.1 to 87.0 F. Hatching occurred at 44.4-84.9 F and was optimum (38% hatched) at about 64 F. Incubation time varied from 15 days at 45 F to 3.7 days at 70 F and 2.1 days at 84 F. Time from start to finish of hatching ranged from 13 days at about 46 F to 2-3 days at 68-70 F and 1-2...

Some hope is returning for recovery of the fish stocks of the Great Lakes, which have been outstanding examples of abuse although they are the world's largest and most valuable freshwater fishery resource. The lakes and the fish in them have been under complete jurisdiction of sovereign nations and their subdivisions almost since the settlement of north-central North America, but...

No abstract available.

Dramatic fluctuations have occurred in the abundance of many species in Lake Erie and its tributary waters in the last century. Some fishes of former economic importance have become commercially extinct. Several species apparently have been extirpated, especially in the tributaries. It is believed that further changes in the abundance of other species will occur in the near future. This

No abstract available.

The sex composition and other biological characteristics of the bloater changed substantially during recent decades of continuous ecological change in Lake Michigan. The percentages of females increased from 72% of the bloaters samples in 1928-32 to 95% in 1963, and ranged from 94 to 97% in 1964-69. The unusual predominance of females was established at an early age, unquestionably...

The zooplankton populations in southeastern Lake Michigan underwent striking, size-related changes between 1954 and 1966. Forms that decline sharply were the largest cladocerans (Leptodora kindtii, Daphnia galeata, and D. retrocurva), the largest calanoid copepods (Limnocalanus macrurus, Epischura lacustris, and Diaptomus sicilis), and the largest cyclopoid copepod (Mesocyclops edax)...

The alewife (Alosa pseudoharengus) has caused serious problems in the Great Lakes for almost 100 years. It entered Lake Ontario in abundance via the Erie Canal during the 1860's when major piscivores were declining, and became the dominant species in the lake during the 1870's. The alewife subsequently spread throughout the Great Lakes and became the dominant species in Lakes Huron and...

During the past 4 years the Ann Arbor Great Lakes Fishery Laboratory of the Bureau of Commercial Fisheries has been monitoring insecticide levels in fish from the Great Lakes. The two insecticides found in all Great Lakes fish have been DDT (DDT, DDD, DDE) and dieldrin. Fish from Lake Michigan contain from 2 to 7 times as much of these insecticides as those from the other Great Lakes...

Hermaphroditism is relatively rare among the Salmonidae (See Atz, 1964 for a comprehensive review) and has never been reported for coregonine fishes. Recent examination of a collection of coregonines at the Great Lakes Fishery Laboratory disclosed a hermaphroditic bloater(Coregonus hoyi). The fish was captured in a gill net set at 50 fathoms on the bottom of Lake Michigan approximately 7...

Experimental hybridization among five species of lampreys of the Upper Great Lakes routinely produced embryos through stage 8, and four crosses produced embryos to the larval stage. Three critical periods in the embryogenesis of hybrid lampreys were between stages 8 and 9, among stages 10, 11, and 12, and at stage 15. Embryonic development in hybrid lamprey embryos is basically identical...