Burbot: Ecology, Management, and Culture

2008 ◽  
Keyword(s):  
Relative Abundance ◽  
Inverse Relationship ◽  
Relative Weight ◽  
Cumulative Effect ◽  
Missouri River ◽  
Population Characteristics ◽  
Sampling Efficiency ◽  
Temperature Regimen ◽  
Catch Rates ◽  
Central Montana

<em>Abstract.</em>—Although burbot <em>Lota lota </em>are native to Montana, little is known about their distribution, life history, and ecology. The objectives of this study were to determine the distribution, relative abundance, and population characteristics of burbot in the upper Missouri River basin in north-central Montana, and to compare sampling efficiency of hoop nets, cod traps, and slat traps. Hoop nets and cod traps were fished in the Missouri River during March 2005 and 2006, and slat traps were fished during March 2006. In total, hoop nets were fished 572 net nights, cod traps for 94 net nights, and slat traps for 92 net nights. Catch rates of hoop nets and cod traps were higher in 2005 than in 2006, and catch rates of all gear types were higher in the upstream half of the study area. Mean section-wide hoop-net catch rates exhibited a significant (<EM>P </EM>≤0.05) inverse relationship with increasing distance downstream from Holter Dam, while catch rates for other gear types did not. Catch rates were not significantly different (<EM>P </EM>≥0.05) among gear types. The size (length and weight) and condition (relative weight) of burbot sampled was significantly (<EM>P </EM>≤0.05) different among gear types. Length, weight, and relative weight were higher for burbot sampled in hoop nets and cod traps than those sampled in slat traps. Slat traps were effective at sampling small (≤300 mm) burbot. Although most (80%) burbot were recaptured within 10 km of where they were tagged, three burbot moved more than 33 km. We hypothesize that the distribution of burbot in our study reach has changed and relative abundance has increased due to the cumulative effect of upstream reservoirs (Canyon Ferry, Hauser, and Holter) by decreasing the downstream water temperature regimen.

scholarly journals Standardizing catch rates: is logbook information by itself enough?

2008 ◽  
Vol 65 (2) ◽  
pp. 255-266 ◽  
Author(s):  
J. Bishop ◽  
W. N. Venables ◽  
C. M. Dichmont ◽  
D. J. Sterling
Keyword(s):  
Relative Abundance ◽  
Prediction Models ◽  
Expert Knowledge ◽  
External Information ◽  
Linear Regression Models ◽  
Catch Per Unit Effort ◽  
Estimation Model ◽  
Catch Rates ◽  
Logbook Data ◽  
Estimation Models

Abstract Bishop, J., Venables, W. N., Dichmont, C. M., and Sterling, D. J. 2008. Standardizing catch rates: is logbook information by itself enough? – ICES Journal of Marine Science, 65: 255–266. The goal of the work was to maximize the accuracy of standardized catch per unit effort as an index of relative abundance. Linear regression models were fitted to daily logbook data from a multispecies penaeid trawl fishery in which within-vessel changes in efficiency are common. Two model-fitting strategies were compared. The predictive strategy focused on maximizing the explained variance, and the estimation strategy on finding realistic coefficients for important components of changing catchability. Realistic values could not always be obtained, because the regression factors were not orthogonal, and data on the presence of technology were sometimes unreliable or systematically incomplete. It was not possible to separate fishing power from abundance by analysing logbook data alone; it was necessary to incorporate external information within the standardization model. Therefore, the resultant estimation models incorporated external information and expert knowledge by offsets. There was no single best estimation model. Instead, a series of models provided an envelope of possible changes in relative fishing power and prawn abundance since 1970. Compared with the prediction models, the estimation models revealed different trends in relative fishing power and relative abundance.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
International Symposium ◽  
Body Condition ◽  
Relative Abundance ◽  
Habitat Restoration ◽  
Missouri River ◽  
Natural State ◽  
Pylodictis Olivaris ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Growth Increments

<em>Abstract</em>.—An assessment of the flathead catfish <em>Pylodictis olivaris</em> population in the Missouri River bordering Nebraska was conducted between 1997 through 2008. The Missouri River was divided into four sections based on physical and geomorphologic uniqueness (upper unchannelized, lower unchannelized, upper channelized, and lower channelized). Two sections were sampled annually, and each section was sampled on alternate years. Boat electrofishing collected 12,846 fish in 83.5 h from 701 sampling stations. Most flathead catfish sampled (98%) were less than 510 mm total length (quality length), with significantly more fish captured in channelized than unchannelized reach. Fish from channelized sections also had higher mean total lengths and larger growth increments but were in poorer body condition than those from unchannelized sections. Low relative abundance of flathead catfish in the upper unchannelized section and scarcity of large individuals were attributed to poor habitat conditions. Habitat restoration along with restoring natural riverine processes would return the river to a more natural state and would not only benefit flathead catfish, but other native Missouri River fishes as well.

Abundance estimation and capture of sablefish (Anoplopoma fimbria) by longline gear

2000 ◽  
Vol 57 (6) ◽  
pp. 1270-1283 ◽  
Author(s):  
Michael F Sigler
Keyword(s):  
Relative Abundance ◽  
Weak Link ◽  
Information Source ◽  
Leading Edge ◽  
Abundance Estimation ◽  
Encounter Rate ◽  
Odor Plume ◽  
Odor Concentration ◽  
Anoplopoma Fimbria ◽  
Catch Rates

Longline surveys in Alaska measure sablefish (Anoplopoma fimbria) relative abundance and are the primary information source used for abundance and quota estimation. Hook timer, on-bottom (soak) time, hook density, hook pattern, bait type, and bait condition experiments and mathematical models were used to evaluate the performance of the longline surveys for estimating sablefish relative abundance. The rate that sablefish encountered the longline gear decreased with on-bottom time independently of sablefish density in the sampled area. Sablefish were adept at locating available baits, even when few remained. The decrease in encounter rate appears related to odor concentration at the leading edge of the odor plume. The ability to locate baits, even when few remain, differs from previous models of fish capture by longline in which the probability that a fish located a bait was proportional to the number of available baits. Decreased encounter rate and the ability to locate baits efficiently imply that longline catch rates likely provide an accurate index of fish abundance if the on-bottom time is long enough to cover the period when most fish encounter the gear and the initial bait density is high enough that baits remain available throughout the soak; the weak link between catch rate and abundance is the unknown extent that factors such as temperature and food availability affect the proportion of fish caught.

Does habitat or depth influence catch rates of pelagic species?

2007 ◽  
Vol 64 (11) ◽  
pp. 1581-1594 ◽  
Author(s):  
Keith A Bigelow ◽  
Mark N Maunder
Keyword(s):  
Relative Abundance ◽  
Environmental Conditions ◽  
Environmental Data ◽  
Catch Per Unit Effort ◽  
Blue Shark ◽  
Species Vulnerability ◽  
Thunnus Obesus ◽  
Catch Rates ◽  
The Relationship ◽  
The Vertical Distribution

The efficiency of a pelagic longline fishing operation and the species composition of the resulting catch is influenced primarily by the relationship between the distribution of hooks and species vulnerability, with vulnerability described by either depth or some suite of environmental variables. We therefore fitted longline catch rate models to determine whether catch is estimated better by vertically distributing a species by depth or by environmental conditions (e.g., temperature, thermocline gradient, and oxygen concentration). Catch rates were estimated by two methods: (i) monitoring longlines where the vertical distribution of hooks and catch in relation to depth and environmental conditions is known, and (ii) applying a statistical habitat-based standardization (statHBS) model to fishery and environmental data to develop relative abundance indices for bigeye tuna (Thunnus obesus) and blue shark (Prionace glauca). Results indicated that an understanding of gear dynamics and environmental influences are important for analyzing catch-per-unit-effort (CPUE) data correctly. Analyses based on depth-specific catch rates can lead to serious misinterpretation of abundance trends, despite the use of sophisticated statistical techniques (e.g., generalized linear mixed models). This illustrates that inappropriate inclusion or exclusion of important covariates can bias estimates of relative abundance, which may be a common occurrence in CPUE analysis.

Effects of wave exposure on the proportion of gametophytes and tetrasporophytes of Mazzaella oregona (Rhodophyta: Gigartinales) from Pacific Canada

2003 ◽  
Vol 83 (4) ◽  
pp. 701-704 ◽  
Author(s):  
Benita Mudge ◽  
Ricardo Scrosati
Keyword(s):  
Population Structure ◽  
Life History ◽  
Population Density ◽  
Relative Abundance ◽  
Inverse Relationship ◽  
Sympatric Species ◽  
Wave Exposure ◽  
High Wave ◽  
Red Seaweeds ◽  
Barkley Sound

The proportion of life history phases in red seaweeds is an important descriptor of population structure. This paper describes the relative abundance of gametophytes and tetrasporophytes of Mazzaella oregona (Rhodophyta: Gigartinales; formerly M. heterocarpa), focusing particularly on the effects of wave exposure on the proportion of both life history phases. In two different rocky points in Barkley Sound (Pacific Canada), gametophytes were, in proportion to tetrasporophytes, relatively more abundant under low wave exposure than under high wave exposure in July 2002, during the period of highest abundance for this species. The inverse relationship between the G:T ratio and the degree of wave exposure also occurs for local M. splendens, but not for local M. parksii. Differences in frond size and population density between these three sympatric species are related to the effects of wave exposure on their G:T ratio.

scholarly journals Population Characteristics and the Potential Suppression of Common Carp in Lake Spokane, Washington

2019 ◽  
Vol 10 (2) ◽  
pp. 362-374 ◽  
Author(s):  
Stacey F. Feeken ◽  
Zachary B. Klein ◽  
Michael C. Quist ◽  
Ned Horner
Keyword(s):  
Common Carp ◽  
Air Temperature ◽  
Population Characteristics ◽  
Minimum Length ◽  
Management Scenarios ◽  
Structured Population Model ◽  
Growth Increments ◽  
Catch Rates ◽  
Variable Recruitment ◽  
Water Elevation

Abstract Common Carp Cyprinus carpio is a nonnative species that often has deleterious effects on aquatic systems. As such, there is interest in suppressing nonnative Common Carp populations in areas where humans have introduced them. The objectives of this study were to 1) provide insight on efficient techniques for capturing Common Carp, 2) describe their population demographics and dynamics, 3) evaluate whether temperature and water elevation were related to growth and recruitment, and 4) develop an age-structured population model for evaluating different management scenarios of Common Carp removal in Lake Spokane, Washington. Catch rates of Common Carp varied among sampling gears with slightly higher catch rates in monofilament (mean ± SD; 15.5 ± 9.8 fish/net night) vs. multifilament (12.7 ± 7.3 fish/net night) gill nets. Catch rates of Common Carp with nighttime electrofishing (0.3 ± 0.4 fish/min) were higher than daytime electrofishing (0.1 ± 0.2 fish/min). Common Carp in Lake Spokane exhibited variable recruitment, rapid growth, large-length structure, high longevity (i.e., age 18 y), and low total annual mortality (17.0%). Air temperature was positively associated with annual growth increments (R2 ≤ 0.25). Neither air temperature nor water elevation was highly correlated (R2 ≤ 0.20) to recruitment of Common Carp. A Beverton–Holt yield-per-recruit model suggested that yield declined with increasing exploitation. Recruitment overfishing would occur at exploitation rates of 20–40% for all targeted minimum length categories (i.e., 150, 300, 450 mm) except 600 mm. Results from this study provide important information on the ecology of Common Carp that can be used to guide management efforts (e.g., suppression) in western systems.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
International Symposium ◽  
Size Structure ◽  
River System ◽  
Population Characteristics ◽  
Blue Catfish ◽  
Growth And Survival ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Management Actions ◽  
Catch Rates

<em>Abstract</em>.—Catfish are popular recreational fish in Alabama, and management interest has been rising. We hypothesized that tailwater habitat more closely resembling lotic conditions would provide more suitable conditions for catfishes compared to impounded habitats. We examined and compared population characteristics, including abundance, age and size structure, growth, and survival of blue catfish <em>Ictalurus furcatus</em>, channel catfish <em>I. punctatus</em>, and flathead catfish <em>Pylodictis olivaris</em> between tailwater and reservoir habitats in a section of the Coosa River in 2001–2002. Coosa River system tailwater habitats appear to generally provide higher quality environments for abundance and growth of catfishes than reservoir habitat, although results were often not consistent among species. We found no differences for many comparisons of stock descriptors between tailwater and reservoir habitat. We found that blue catfish were larger (48 mm total length larger) and flathead catfish electrofishing catch rates were higher (13 fish/h greater) in tailwater areas. Catfish populations in the Coosa River were characterized by slow growth and high longevity, findings in accord with other recent otolith-based age analyses from populations in the Southeast. All species had moderate to high annual survival (57–88%), likely indicating light exploitation levels. Catfish populations in this section of the Coosa River appear robust, and the tendency for these dam tailwaters to have higher quality catfish populations may warrant management actions to enhance/sustain these fisheries.

Evaluation of quota management policies for developing fisheries

1998 ◽  
Vol 55 (12) ◽  
pp. 2691-2705 ◽  
Author(s):  
Carl Walters
Keyword(s):  
Mortality Rate ◽  
Relative Abundance ◽  
Cumulative Effect ◽  
Mortality Rates ◽  
Reference Trajectory ◽  
Fishing Mortality ◽  
Small Probability ◽  
Abundance Indices ◽  
Management Policies ◽  
Quota Management

Losses can be measured as deviations from a desired reference trajectory of quotas that would be taken if there were no uncertainty and are highly dependent on assessments prior to and during development. Simulations of assessment and quota setting under various quota setting rules indicate that variability in relative abundance indices can cause substantial losses, especially considering cumulative effect of early quota errors on later departures of biomass from that needed to produce the desired quotas, even if optimum fishing mortality rate is known in advance. Conservative assessments (low biomass estimates for which there is only a small probability that biomass is actually lower) are favored during development when loss is measured as the relative departure from the best quota for each year. But if loss is measured as absolute departure from the best quota, it is generally better to base the quota on the biomass estimate for which there is nearly a 50% chance that the stock is smaller. Deliberate overfishing (probing) is not favored under either loss measure. Losses can be reduced with minimum biomass surveys and closed areas that directly cushion fishing mortality rates from being more than 50% too low or high.

The sugar intake of businessmen and its inverse relationship with relative weight

1972 ◽  
Vol 27 (3) ◽  
pp. 449-460 ◽  
Author(s):  
J. F. Richardson
Keyword(s):  
Inverse Relationship ◽  
Direct Relationship ◽  
Relative Weight ◽  
Positive Association ◽  
Sugar Consumption ◽  
Self Administration ◽  
Future Studies ◽  
Actual Weight ◽  
Sugar Intake

1. Yudkin's (1967) questionnaire on the dietary intake of sugar was given to 415 businessmen for self-administration.1. The results showed an inverse relationship between sugar intake and relative weight (actual weight as a percentage of expected weight for height and age) and additional evidence suggests a direct relationship between sugar intake and adequate exercise.2. The statement that ‘sugar was restricted’ was shown to be a factor of considerable importance affecting the reported level of sugar intake and should be taken into account when comparing different series.3. The positive association between cigarette smoking and mean sugar consumption in this series was due to the low-sugar intake of ex-smokers.4. In future studies on the role of sucrose in the aetiology of ischaemic disease, both smoking habits and levels of activity should be recorded.

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