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At least 19 recordsLinked to original sources
USGS2019

Observations of American Shad Alosa sapidissima approaching and using a vertical slot fishway at the head-of-tide Brunswick Dam on the Androscoggin River, Maine

American Shad Alosa sapidissima have historically supported an important fishery along the Atlantic coastal waters of North America. However, the construction of dams reduced populations and restricted landings. Fishways are intended to mitigate obstacles to anadromous fish migrations, but a thorough evaluation of their efficiency is warranted. We analyzed data collected from video recordings, hydropower turbine operations, and telemetry conducted by the Maine Department of Marine Resources to evaluate American Shad behavior while approaching and using a vertical slot fishway at the head-of-tide Brunswick Dam on the Androscoggin River in Maine. American Shad passage at the dam has been poor, ranging from 0 to 1,100 fish per year, relative to passage at other facilities in the region. Additionally, our observations indicate that there are relatively high numbers of American Shad present downstream in the river (averaging 50,000) compared with the entrance of the fishway or its pools (<8,000). On average, the rates of observed American Shad on the side of the river near the fishway entrance were significantly higher (6.5–8.6 individuals/min) when the turbine closest to the entrance of the fishway was not operating compared with when it was operating (4.1 individuals/min). Most of the radio-tagged American Shad remained in the river below the dam or went undetected. Eleven of 57 tagged fish were detected at the fishway entrance and of those only five were detected in the lower fishway. Individuals that were detected were observed making multiple attempts at entering the fishway, but movements were restricted to the lower pools. Our results suggest that this fishway is not conducive to the passage of American Shad. Examining the relationship between hydropower operations and other environmental variables on the behavior and passage of migrating anadromous fish remain an area for further study.

Maine↗
USGS2013

New insights into the diets of harbor seals in the Salish Sea revealed by quantitative fatty acid signature analysis

Harbor seals ( Phoca vitulina ) are an abundant predator along the west coast of North America, and there is considerable interest in their diet composition, especially in regard to predation on valued fish stocks. Available information on harbor seal diets, primarily derived from scat analysis, suggests that adult salmon ( Oncorhynchus spp.), Pacific Herring ( Clupea pallasii ), and gadids predominate. Because diet assessments based on scat analysis may be biased, we investigated diet composition through quantitative analysis of fatty acid signatures. Blubber samples from 49 harbor seals captured in western North America from haul-outs within the area of the San Juan Islands and southern Strait of Georgia in the Salish Sea were analyzed for fatty acid composition, along with 269 fish and squid specimens representing 27 potential prey classes. Diet estimates varied spatially, demographically, and among individual harbor seals. Findings confirmed the prevalence of previously identified prey species in harbor seal diets, but other species also contributed significantly. In particular, Black ( Sebastes melanops ) and Yellowtail ( S. flavidus ) Rockfish were estimated to compose up to 50% of some individual seal diets. Specialization and high predation rates on Black and Yellowtail Rockfish by a subset of harbor seals may play a role in the population dynamics of these regional rockfish stocks that is greater than previously realized.

British Columbia, Washington↗
USGS2015

Effects of oyster harvest activities on Louisiana reef habitat and resident nekton communities

Oysters are often cited as &ldquo;ecosystem engineers&rdquo; because they modify their environment. Coastal Louisiana contains extensive oyster reef areas that have been harvested for decades, and whether differences in habitat functions exist between those areas and nonharvested reefs is unclear. We compared reef physical structure and resident community metrics between these 2 subtidal reef types. Harvested reefs were more fragmented and had lower densities of live eastern oysters ( Crassostrea virginica ) and hooked mussels ( Ischadium recurvum ) than the nonharvested reefs. Stable isotope values ( 13 C and 15 N) of dominant nekton species and basal food sources were used to compare food web characteristics. Nonpelagic source contributions and trophic positions of dominant species were slightly elevated at harvested sites. Oyster harvesting appeared to have decreased the number of large oysters and to have increased the percentage of reefs that were nonliving by decreasing water column filtration and benthopelagic coupling. The differences in reef matrix composition, however, had little effect on resident nekton communities. Understanding the thresholds of reef habitat areas, the oyster density or oyster size distribution below which ecosystem services may be compromised, remains key to sustainable management.

Louisiana↗
USGS2018

The influence of nutrients from carcasses of sea lamprey (Petromyzon marinus) on larval growth and spawner abundance

Migrations of anadromous sea lamprey (Petromyzon marinus) from marine ecosystems serve as vectors of nutrients into freshwater food webs. Larval sea lamprey reside in streams for 6–8 years as deposit feeders before metamorphosing into juveniles and migrating to the ocean. Previous work has shown that carcass nutrients, which result from the death of adult lamprey after spawning, increase stream productivity and are consumed by larvae. This may increase larval growth rates and enhance earlier metamorphosis. We examined the sensitivity of life-history parameters and influence of nutrients from carcasses of sea lamprey on the age and growth of larval conspecifics with a deterministic stock-recruitment model. We hypothesized that variability in growth among larval populations is productivity mediated and we compared modeled populations in which larvae receive added growth benefits from carcass nutrients with populations that do not. The results of our simulation indicate that increases in larval growth and lower age at metamorphosis over time lead to an increase in spawner abundance. Increased growth rates may also improve fitness and bolster subsequent spawning stocks. Our research characterized 2 potential ecosystem states, one in which larval sea lamprey benefit from adult conspecifics and another in which the larvae do not.

Fishery Bulletin↗
USGS2018

Movement and mortality of Atlantic salmonkelts (Salmo salar) released into thePenobscot River, Maine

The Penobscot River is home to the last major run of Atlantic salmon (Salmo salar) in the United States. For over one century, the river has been stocked intensively. Since the late 1970s, most kelts are released to the Penobscot River estuary following spawning in a hatchery. Over that time, the proportion of the run made up of iteroparous individuals has declined to < 1%. These fish may make a disproportionate contribution to the spawning population because they are typically large and produce more eggs than virgin spawners. We radio-tagged 55 kelts that were artificially spawned at the Craig Brook National Fish Hatchery in 2015 and released them in two different locations in the river (head of tide and ~50 km upstream) to assess 1) when hatchery-spawned kelts leave the river, 2) whether release location influences river exit timing, and 3) if kelts from the upper river could successfully outmigrate through the lower Penobscot River’s hydroelectric complex. The kelts were tracked from November 2015 to July 2016. Although some fish from both release groups were documented leaving the system within one month, the majority of fish (84%) overwintered in freshwater habitat. Many (71%) of those kelts that overwintered in the Penobscot River made directed, upstream movements in November and December. However, there was no difference in upstream movement rates, timing of outmigration, or survival between the release groups. Survival to outmigration was 23.6%, which is considerably lower than kelt survival documented in Canadian and European rivers. Low survival to outmigration may have contributed to the disappearance of iteroparous individuals from the Penobscot River run of Atlantic salmon over the last four decades.

Maine↗
USGS1963

Age, growth, and maturity of round whitefish of the Apostle Islands and Isle Royale Regions, Lake Superior

The round whitefish has been of some commercial importance in the upper Great Lakes but production in Lake Superior has generally been small; the United States average was 26,600 pounds for 1929-59. This study is based on 1,173 fish collected in the Apostle Islands in 1958-60 and 103 collected at Isle Royale in 1958 and 1960. The average age of 6.0 years at Isle Royale was concluded to be significantly higher than the mean of 4.2 years in the Apostle Islands. The body-scale relation is a straight line with an intercept of 1.1 inches on the length axis. Weight of Apostle Islands round whitefish captured in several months increased as the 3.22 power of the length. Growth in length was relatively slow; nearly or fully 7 years were required to reach an acceptable commercial length of 14 inches in both the Apostle Islands and at Isle Royale. The calculated weights at the end of the seventh year were 12.6 ounces in the Apostle Islands and 13.8 ounces at Isle Royale. Minimum length at maturity of male round whitefish (7.0-7.4 inches) was less than that of females (8.5-8.9 inches). At age-group II, 11.1 percent of male round whitefish, but only 1.5 percent of the females were mature. All males were mature as age-group V and all females as age-group VI. Males dominated the younger age groups but females were more numerous in the older ones. Estimates of the number of eggs in 37 round whitefish ovaries yielded an average of 5,330 eggs for fish 10.5-17.4 inches long.

Fishery Bulletin↗
USGS1966

Life history of the gizzard shad, Dorosoma cepedianum (Le Sueur), in western Lake Erie

The rapid increase in the stocks of gizzard shad in Lake Erie since 1950 unquestionably had an important effect on the ecology of the lake. The present study, based on almost 24,000 fish collected by various means in 1952-55 in or near the island area of western Lake Erie was undertaken to provide information on the role of shad in the bionomics of the region. The annulus of the gizzard shad scale is a valid year-mark. It is laid down in May-July, a little later in the older than in the younger fish. The body-scale relation is linear with an intercept of 22.1 mm. on the axis of standard length. Age-groups 0, I, and II were abundantly represented in the samples. Age-group III was much less well represented, and older fish were extremely scarce. The oldest shad seen belonged to the VI-group. The seasonal growth was most rapid in July-August and growth was much reduced or nil in January-April. Males attained the following average standard lengths (in millimeters) at the end of the indicated years of life: 1-141; 2-273; 3-313; 4-343; 5-349. For females these values were 1-140; 2-285; 3-335; 4-364; 5-386. The weight of the gizzard shad increased as the 3.07053 power of the length. The length-weight relation varied seasonally, annually, and, near the spawning season, according to sex and state of gonads. Only a few precocious male and female gizzard shad attain sexual maturity as age-group I. Almost all males and a good percentage of females mature at age II and only rarely are III-group shad immature. Development of the egg and seasonal changes of the ovary are described. Egg production is highest in the II group-average of 378,900 per individual and 689 per gram of body weight. Spawning takes place from early June into July and is most intensive near mid-June. Heaviest spawning is at water temperatures of 67A?F. or more. Early development to the attainment of the adult shape is described; particular attention is given to the development of the alimentary tract. The anatomy of the digestive tract in the adult is described, and comments are offered on the function of such organs as the pharyngeal pouches and the caeca. Tests were made for digestive enzymes in different parts of the tract. The gizzard shad is a filter feeder. Food varies widely with season and locality but consists mostly of phytoplankton and zooplankton.

Fishery Bulletin↗
USGS1964

Movements, growth, and rate of recapture of whitefish tagged in the Apostle Islands area of Lake Superior

A total of 1,303 whitefish were marked with spaghetti streamer tags in Wisconsin waters off Lake Superior in November of 1959, 1960, and 1961 and June-July 1960. The fish tagged in June-July 1960 were mostly undersized (less than 17 inches long) whereas those captured on the spawning grounds and tagged in November 1959-61 were almost all legal size. Of the 374 recoveries (28.7 percent), nearly all were made during the first 2 years after tagging. The earliest returns were from fish which were among the largest when tagged. Over one-half of the recoveries were made within 5 miles of the tagging site; the greatest distance traveled by an individual was 25 miles. The fish tagged in June-July 1960 grew 1.6 inches the first season and 1.2 the second. Of 27 whitefish recaptured within 6 months from the November 1959-61 group, 17 (63 percent) had lost length (range from decrease 0.1 to 1.4 inches). Whitefish of the June-July group recaptured during the second growing season after tagging gave an exploitation rate of 22.6 percent. First-year returns from the November 1959-61 tagging gave an exploitation rate of 20.5 percent. The true exploitation rate probably is higher since no allowance has been made for tagging mortality, loss of tags, or unreported recaptures.

Fishery Bulletin↗
USGS1964

Life history of lake herring in Lake Superior

The average annual commercial catch of lake herring (Coregonus artedi) in U.S. waters of Lake Superior was nearly 12 million pounds in 1929-61. This production contributed 62.4 percent of the total U.S. take of lake herring for the Great Lakes. About 90 percent of the annual catch is taken from small-mesh gill nets during the November-December spawning season. The life-history studies were based on 12,187 fish collected in 1950-62; past growth was computed for 3,779 specimens collected from commercial landings at: Duluth, Minn.; Bayfield, Wis.; and Portage Entry and Marquette, Mich.

Fishery Bulletin↗
USGS1963

Age and growth of the whitefish in Lake Superior

The average annual commercial production of whitefish in the U.S. waters of Lake Superior dropped from 2,194,000 pounds in 1879-1908 to 504,000 pounds in 1911-59. The modern production, though far below the earlier, has accounted for more than 10 percent of the total value of the fishery in all but one of the last 20 years. Data are given on growth rate, age and year-class composition, size distribution, and length-weight relation of 1,800 fish collected in 1957-59 at Bayfield, Wis., and Marquette, Whitefish Point, and Dollar Settlement, Mich. Studies of the body-scale relation, sex ratio, and age and size at maturity were limited to fish collected at Bayfield. The age composition and mean age varied widely by port and year of capture. Oldest fish were those of the 1957 Bayfield samples which were dominated by age group VII and averaged 5.5 years old. The youngest were from Whitefish Point in 1959; age-group III was dominant, and the mean age was 3.2 years. The evidence on the strength of year classes was not clear-cut, but it was obvious that fluctuations in stocks of different areas were largely independent. The percentage of legal-size fish (17 inches or longer) in age groups ranged widely; only 8.6 percent of the V group were legal in the 1957 Bayfield collections, whereas 100 percent of fish of the same age were legal in the 1957-59 collections from Whitefish Point. The weight of whitefish in the combined samples increased as the 3.2408 power of the length. The growth rate from the fastest to the slowest growing stocks ranked as follows: Whitefish Point; Dollar Settlement and Marquette (fish from the two ports reversed ranks after 3 years); Bayfield. The major differences in growth in length among the various stocks occurred during the first years of life. Beyond the fifth year the annual increments were nearly the same in all stocks. The whitefish from Whitefish Point, Dollar Settlement, and Marquette are among the fastest growing in the Great Lakes. The differences among the Lake Superior stocks in age and year-class composition, and in growth rate offer convincing evidence that populations of different areas are entirely independent. The sexes were almost equally represented (51.5 percent males) in the combined Bayfield samples, but males were scarce in age groups older than VIII. Whitefish from Bayfield shorter than 14.5 inches were immature and those larger than 17.4 inches were mature. The youngest mature fish belonged to age-group V,and all older than the VII group were mature.

Fishery Bulletin↗
USGS1959

Fluctuations in the population of yellow perch, Perca flavescens(Mitchill), in Saginaw Bay Lake Huron

SUMMARY: The value of a line of traps as a measure of relative abundance of small mammals was studied by field trials on Peromyscus leucopus populations. Comparisons were made between the numbers of mice captured by a line of live traps and the numbers captured in intensive live trapping of a larger area surrounding the line. Trials were made in bottomland woods where mice were numerous and in upland woods where mice were less common. It was found that wood mice living in upland woods had significantly larger cruising ranges than those living in bottomland woods. Consequently, a line of traps in the bottomlands captured mice from a smaller surrounding territory than in the uplands. Therefore, comparisons of relative size of the mouse population in these two areas on the basis of line-trapping showed an erroneously large number for the upland woods. As a result of these trials and the studies of other workers, it is concluded that lines of traps are not fully reliable means of measuring relative abundance of small mammals.

Fishery Bulletin↗
USGS1953

Fluctuations in the fisheries of State of Michigan waters of Green Bay

Green Bay, traditionally a major center of production, has assumed in recent years a position of overwhelming dominance in the commercial fisheries of the State of Michigan waters of Lake Michigan. Within the 4-year period 1945-1948 the commercial take in State of Michigan waters of Green Bay increased from 3,317,000 pounds in 1945 to 7,909,000 pounds in 1948, and it was 7,782,000 poinds in 1949. At the same time the percentage contribution of Green Bay to the State total for Lake Michigan rose each year, increasing from 36.5 in 1945 to 65.4 in 1949. The tremendous upswing in commercial production in Green Bay can be attributed to the abnormally high abundance of three important species--the lake whitefish (Coregonus clupeaformis), the lake herring or shallowwater cisco (Coregonus [=Leucichthys] artedii), and the walleye or yellow pikeperch (Stizostedion v. vitreum)--and to a marked rise in fishing intensity.

Fishery Bulletin of the U.S. Fish and Wildlife Ser↗