Showing papers on "Fish migration published in 1975"

Biotic passage through the Panama Canal, with particular reference to fishes

Abstract: The effectiveness of the Gatun Lake fresh-water barrier to fish migration of the Panama Canal was examined, based on literature records and recent collections. Six species have migrated to the Pacific and three to the Atlantic Oceans. New records include: Hypleurochilus aequipinnis, Barbulifer ceuthoecus and Oostethus lineatus of Atlantic origin, and Gnathanodon, speciosus of Pacific origin. The majority of Atlantic migrants are known in the Pacific only from the Miraflores Third Lock, a unique ectogenic meromictic lake attached to the Pacific entrance of the canal. The hydrography and biota (including Atlantic algal and crustacean species previously unknown as canal migrants) of the lake are discussed. It is presumed that certain fish migrants transited the canal by associating with fouling material on the underside of ships. The euryhaline species, H. aequipinnis, Lupinoblennius dispar, Lophogobius cyprinoides and Omobranchus punctatus survived in freshwater (0.0‰S) for periods longer than required for ship transit of the canal (ca. 8h). The stenohaline migrant Gobiosoma nudum died after 2 h in freshwater, but survived more than 50 h at 2.5‰S. Plans to increase Panama Canal ship transits through the pumping of seawater into Gatun Lake might remove the biological barrier and allow the migration of euryhaline and stenohaline species. We find those plans unwise, and the potential consequences dangerous.

Late Period Settlement of the Middle Klamath River of Northwest California

Abstract: A settlement pattern study is made of 160 prehistoric habitation sites along the Klamath river in northwest California to determine what environmental factors regulate site placement and population density. Topographic variables, especially gradient, were found to serve as negative criteria in limiting the possibilities of site location. Differential access to anadromous fish was found to function positively in favoring site placement and high population density. This finding supports Baumhoff's hypothesis that Karok population levels could be accounted for by available fish resources alone (Baumhoff 1963).

Biology and management of river herring and shad in Virginia : Annual report, Anadromous Fish Project 1974

Abstract: Year class strength estimates of alewife, blueback herring and American shad were compared to landings and catch-per-effort estimates of the parents in the major freshwater nursery zone of the James, York, Rappahannock and Potomac rivers of Chesapeake Bay. There was no direct parent-progeny relationship for any species in any river, although adult landings of shad (females) below 150,000 pounds per season usually coincided with weak year classes. The James River was the most productive for young alosines over the period of record. The density of juveniles in the James River exceeded the other rivers by 15 to 70 times depending on year and species .. The Potomac, with far less densit~ produce~ more young alosid~ than in the more productive York and Rappahannock because of its large nursery zone. Over the last five years the total estimated number of juvenile alosids present in early fall ranged between 73 and 1969 million for all rivers.

Natural resources of Lake Earl and Smith River Delta

Abstract: The Lake Earl/Smith River Delta area is a key coastal wetland situated in northern California. The Lake and Delta have retained much of their value to wildlife and serve as an important link in a chain of such wetlands that extend southward along the Pacific Ocean from Alaska to South America. Millions of water-associated birds of the Pacific Flyway utilize these areas as feeding and resting stops along their migration paths. In California, these wetlands also serve as a significant portion of the available wintering grounds for a major share of the birds within the flyway. The Smith River is also one of the State's most productive salmon and steelhead streams. Anadromous fish produced here provide thousands of angler use days to sport fishermen and contribute substantially to the commercial fishing catch off the northern coast. Because of the importance of coastal wetlands to the fish and wildlife of California, the Department of Fish and Game has initiated a high priority statewide inventory and assessment of these wetlands. This publication is an integral part of that program. This report identifies specific resources and uses; directs attention to problems; and recommends courses of action needed to insure resource protection. It is intended as a guide for citizens, planners, administrators and other interested in the use and development of California's coastal land and waters. (132pp.)