Feeding mechanism of the sea lamprey and its effect on host fishes
Abstract has not been submitted
SEARCH · Geology Reports
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Abstract has not been submitted
No abstract available.
Abstract has not been submitted
This study is based on 1,023 whitefish, Coregonus clupeaformis (Mitchill)--819 in seven samples from five localitites in central Green Bay in 1948-49 and 1851-52 and 204 in a single 1948 collection from northwestern Lake Michigan proper. Records of age indicated unusual strength for only one year class--1943 which strongly dominated the 1948 sample from Lake Michigan and the 1949 sample from Green Bay and was well represented in the 1948 collection from green Bay. Collection of 1951-52 without exception were dominated by age group III. Length distributions of samples varied widely according to the age composition. Among fish more than 2 years old, the length distributions of age groups overlapped broadly. Several 1-inch intervals included fish of four age groups. The length-weight relation varied considerably among central Green Bay samples, but differences among localitites were nearly equalled by the year-to-year difference at a single locality. Lake Michigan whitefish were generally lighter than those from Green Bay. Weight increased to the 3.386 power of length in Green Bay (combined samples) and the 3.359 power in Lake Michigan. Growth in length, calculated by direct proportion from diameter measurements of growth fields on scales, differed among localities in central Green Bay and between samples of different years at a single locality. If permanent locality differences exist they are not large and can be obscured by the evident annual fluctuations of growth. The grand average calculated length of Green Bay whitefish (combined collections) exceeded that of Lake Michigan fish in all years of life. The advantage was greatest (2.2 inches) at 3 years (calculated lengths of 16.0 inches and 13.8 inches) and subsequently declined to 0.5 inch at 9 years (lengths of 24.6 and 24.1 inches). Both groups reached the minimum legal length of 17 inches during the fourth growing season. Green Bay whitefish also had the larger calculated weights. The advantage reached 9.3 ounces in 3 years (calculated weights of 22.4 and 13.1 ounces). In years of life 4-9, the weight advantage over Lake Michigan fish ranged from 8.7 ounces, (seventh year; weights of 74.4 and 65.7 ounces) to 12.2 ounces (ninth year; weights of 96.2 and 84.0 ounces). Comparison of growth of whitefish at four localities in northern Lake Michigan indicates that fastest growth is in central Green Bay and slowest near the Fox Islands. Growth is intermediate and similar in northwestern Lake Michigan proper and sorthern Green Bay. Youngest mature male whitefish in green Bay belonged to age group II and youngest mature females to age group III. All IV-group fish were mature. Shortest mature males were at 14.5-14.9 inches and shortest mature females at 16.5-16.9 inches. All males longer than 17.9 inches and all females longer than 18.4 inches were mature.
This study is based on systematic seasonal bottom trawling between 3 and 50 fathoms (5.5 and 91.5 m.) from February to November 1964 and supplementary information from other experimental fishing at additional depths and with other gear. The seasonal depth distribution of eight common species is described, and temperature relations are discussed. Catch records for less common species are mentioned briefly. Alewives are mostly pelagic during their first 2 years, but many young of the year are on the bottom in the fall, and yearlings occasionally descend to the bottom in substantial numbers in the spring and fall. Adults are mostly on the bottom in the winter and spring, but a significant portion of the population may be at mid-levels in the summer and fall. Bloaters are in midwater during their first 2 years, but usually on the bottom thereafter. Young-of-the-year American smelt are in midwater except in the fall, yearlings are in midwater or on the bottom, and adults are mostly on the bottom. Alewives, bloaters, smelt, spottail shiners, trout-perch, and yellow perch on the bottom moved into shallower water in the spring and into deeper water in the fall, in response to temperature changes. Slimy sculpins abandoned inshore areas as water warmed in the spring. Fourhorn sculpins showed a slight movement shoreward in the spring, but changed their depth distribution little thereafter to the end of the trawling season. Alewives showed the greatest seasonal change in distribution. Large concentrations at 40 to perhaps 70 fathoms (73.2-128.0 m.) in mid-March had migrated to water of less than 15 fathoms (27.4 m.) by mid-April. They were in shallow water along shore or in rivers until early summer; then they began a postspawning movement back into deeper water which continued into the fall. Depth ranges in which greatest numbers of other common species occurred, considering all seasons as a whole, were as follows: bloater, 12 to 50 fathoms (21.9-91.5 m.); American smelt, 5 to 17 fathoms (9.1-31.1 m.); spottail shiners, 3 to 15 fathoms (5.5-27.4 m.); trout-perch, 5 to 17 fathoms (9.1-31.1 m.); yellow perch, 3 to 15 fathoms (5.5-27.4 m.); slimy sculpins, 15 to 40 fathoms (27.4-73.2 m.); fourhorn sculpins, 45 to 70 fathoms (82.2-128.0 m.). Water temperature ranges (A? C.) in which the various species were most abundant in summer were: alewife, 8 to 22; bloater, 6 to 10; smelt, 6 to 14; spottail shiner, 13 to at least 22; trout-perch, 10 to 16; yellow perch, 11 to at least 22; slimy sculpin, 4 to 6; fourhorn sculpin, 4 to 4.5. Fluctuations in inshore water temperatures in the summer caused short-term changes in depth distribution.
Stomach contents were examined for 794 young-of-the-year (0-group) walleyes (Stizostedion vitreum vitreum) captured by trawls at 17 locations in western Lake Erie in June-November 1962. Food organisms were found in 92.5 percent of the stomachs. Food varied with geographic location and season of capture, but within areas and seasons, selection for certain species and sizes of prey was strong. Walleyes from the extreme western end of Lake Erie fed primarily on gizzard shad and alewives during the summer and shifted to emerald shiners during the fall. The stomach contents of walleyes from the Island region changed from mainly yellow perch during the summer to emerald shiners by the end of the year. Walleyes collected east of the Islands had consumed only smelt and yellow perch. The numbers of forage species caught with walleyes in trawls showed little correlation with the representation of these species in walleye stomachs. Walleyes fed on the smallest individuals of each species regardless of species preferences.
Abstract has not been submitted
The northern lampfish ( Stenobrachius leucopsarus , family Myctophidae) and northern smoothtongue ( Leuroglossus schmidti , family Bathylagidae) are mesopelagic fishes, defined by their vertical distribution in the mesopelagic zone (200–1000 m) during daylight hours. Northern lampfish range from the Bering Sea to southern California (Shimada, 1948), where their abundance is highest along the continental slope and decreases over the continental shelf. They are the most abundant species in the mesopelagic zone of the Bering Sea (Pearcy et al., 1977; Sobolevsky et al., 1996), the Gulf of Alaska (Purcell, 1996), and the eastern North Pacific Ocean off Oregon (Pearcy, 1964; Pearcy et al., 1977). Northern smoothtongue also concentrate in areas bordering the continental slope and are widely distributed from southern British Columbia to the Bering Sea (Peden, 1981) and are very abundant in the Okhotsk Sea (Sobolevsky et al., 1996).
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
No abstract available at this time
No abstract available at this time
No abstract available at this time
This study of the whitefish fishery of Lakes Huron and Michigan includes: (1) a review of the available statistics of production, 1879-1942; (2) a detailed analysis of the annual fluctuations in the production and abundance of whitefish and in the intensity of the whitefish fishery in the State of Michigan waters of the lakes, 1929-1942, with special reference to the effects of fishing with deep trap nets; (3) an account of the bathymetric distribution and vertical movements of whitefish and certain other species; and (4) a report of field observations made in 1931 and 1932, as related particularly to the destruction of undersized whitefish by pound nets and deep trap nets. The main body of the manuscript and appendices A, B, and C, completed in March 1942, contain statistics through the year 1939. Since that time, records for the years 1940-1942 have become available. Because these additional data did not alter any of the conclusions of the manuscript but actually strengthened them, it was not deemed justifiable to expend the considerable amount of time and money that would be required to revise the study. The 1940-1942 records are therefore presented in appendix D. From a relatively high production in the earlier years of the period, 1879 to 1942, the yield of whitefish declined to a lower level about which the catch fluctuated until the late 1920's and early 1930's when a general increase in production occurred. This recent increase was higher and the subsequent decline more severe in the Michigan waters of Lake Huron than in other areas.
Nearshore and shelf fish communities were studied in three areas of lower Cook Inlet, Alaska: the Barren Islands (oceanic and well-mixed waters), Kachemak Bay (mixed oceanic waters with significant freshwater runoff), and Chisik Island (estuarine waters). Fish were sampled with beach seines (n=413 sets) and midwater trawls (n=39 sets). We found that lower Cook Inlet supported a diverse nearshore fish community of at least 52 species. Fifty of these species were caught in Kachemak Bay, 24 at Chisik Island, and 12 at the Barren Islands. Pacific sand lance dominated Barren Islands and Kachemak Bay nearshore habitats, comprising 99% and 71% of total individuals, respectively. The nearshore Chisik Island fish community was not dominated by any one species; instead it exhibited higher diversity. These spatial differences appeared linked to local oceanographic regimes and sediment influx. Analysis of historical data revealed that the nearshore Kachemak Bay fish community changed significantly between 1976 and 1996, showing increased diversity and abundance in several taxa, notably gadids, salmonids, pleuronectids, and sculpins. Decadal differences appeared to be related to large-scale climate changes in the North Pacific. Catches of most taxa peaked in May-August, and were low during other months of the year. Several species were present for only part of the summer. Species composition of seine catches differed significantly between consecutive high and low tides, but not between consecutive sets or years. Midwater trawls took 26 species, 14 of which were present in Kachemak Bay, 19 near Chisik Island, and 7 at the Barren Islands. Community structures in shelf and nearshore waters were similar: diversity was high and abundance low at Chisik Island, whereas a few abundant species dominated at both Kachemak Bay and the Barren Islands. In addition, the low fish abundance near Chisik Island appeared to be related to declining seabird numbers at this colony.
The use of strontium-to-calcium (Sr/Ca) ratios in otoliths is becoming a standard method to describe life history type and the chronology of migrations between freshwater and seawater habitats in teleosts (e.g. Kalish, 1990; Radtke et al., 1990; Secor, 1992; Rieman et al., 1994; Radtke, 1995; Limburg, 1995; Tzeng et al. 1997; Volk et al., 2000; Zimmerman, 2000; Zimmerman and Reeves, 2000, 2002). This method provides critical information concerning the relationship and ecology of species exhibiting phenotypic variation in migratory behavior (Kalish, 1990; Secor, 1999). Methods and procedures, however, vary among laboratories because a standard method or protocol for measurement of Sr in otoliths does not exist. In this note, we examine the variations in analytical conditions in an effort to increase precision of Sr/Ca measurements. From these findings we argue that precision can be maximized with higher beam current (although there is specimen damage) than previously recommended by Gunn et al. (1992).
[No abstract available]