Fishing power increases from technological development in the Faroe Islands longline fishery

2011 ◽  
Vol 68 (11) ◽  
pp. 1970-1982 ◽  
Author(s):  
Ole Ritzau Eigaard ◽  
Bjarti Thomsen ◽  
Holger Hovgaard ◽  
Anders Nielsen ◽  
Adriaan D. Rijnsdorp
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Technological Development ◽  
Melanogrammus Aeglefinus ◽  
Faroe Islands ◽  
Longline Fishery ◽  
Catch Per Unit Effort ◽  
Total Allowable Catch ◽  
Input Control ◽  
Generalized Linear Modelling

During an effort-regulated period from 1996 to 2002, unregistered annual increases of 0.3% of hooks fished per day were demonstrated for the Faroe Islands longline fishery. However, annual increases were higher (1.5%) during a preceding total allowable catch regulated period, thereby invalidating an expectation of the 1996 shift in regulations (output to input control) to have induced increases in the number of hooks set per day. Underlying this result is a substantial increase in total yearly effort (fishing days) and a shift in targeting behaviour from secondary to primary (high value) target species in response to the transition from output to input control. Interview data on technology were combined with logbook data and analysed with generalized linear modelling to demonstrate haddock ( Melanogrammus aeglefinus ) and Atlantic cod ( Gadus morhua ) catch-per-unit-effort increases of 51% and 26%, respectively, following the introduction of skewed hooks and swivel line. The technological introductions were not correlated to regulation shifts. So, rather than the management system in force, an ongoing technological development seems to be the principal driver of fishing power trends. The results highlight the need to explicitly address technological development and targeting behaviour when attempting to meet conservation objectives through input control of fisheries.

scholarly journals Comparative evaluation of a mixed-fisheries effort-management system based on the Faroe Islands example

2010 ◽  
Vol 67 (5) ◽  
pp. 1036-1050 ◽  
Author(s):  
Alan Baudron ◽  
Clara Ulrich ◽  
J. Rasmus Nielsen ◽  
Jesper Boje
Keyword(s):  
Management System ◽  
Comparative Evaluation ◽  
Gadus Morhua ◽  
Evaluation Model ◽  
Regulation System ◽  
Melanogrammus Aeglefinus ◽  
Faroe Islands ◽  
Total Allowable Catch ◽  
Strategy Evaluation ◽  
Short And Long Term

AbstractBaudron, A., Ulrich, C., Nielsen, J. R., and Boje, J. 2010. Comparative evaluation of a mixed-fisheries effort-management system based on the Faroe Islands example. – ICES Journal of Marine Science, 67: 1036–1050. Total allowable catch (TAC) management has in many fisheries, especially mixed fisheries, failed to meet conservation objectives. For instance, for the Faroe Plateau mixed demersal fisheries, the TAC system failed to achieve the objective of an average annual fishing mortality of 0.45 for the three gadoid stocks cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and saithe (Pollachius virens). Therefore, in 1996, an effort-regulation system with individual transferable effort quotas was introduced to manage the fisheries. Experience has shown that effort management without additional stock-specific measures may not be appropriate for such fisheries. A management strategy evaluation model was developed to compare an effort-management system based on the Faroese example with a TAC system as currently applied in EU fisheries. Results show that when stocks are considered in isolation, a total allowable effort system does not necessarily perform better than a TAC one. It depends on stock status and dynamics, the level of uncertainty, and the reactivity of the system to changes in scientific advice. When the stocks are considered together in mixed fisheries, effort management seems, however, to be appropriate, and interannual flexibility of the system appears to be the best compromise between short- and long-term objectives, as well as between biological sustainability and economic return.

Effects of sex, stock, and environment on the shape of known-age Atlantic cod (Gadus morhua) otoliths

2004 ◽  
Vol 61 (2) ◽  
pp. 158-167 ◽  
Author(s):  
M Cardinale ◽  
P Doering-Arjes ◽  
M Kastowsky ◽  
H Mosegaard
Keyword(s):  
Shape Analysis ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Fourier Descriptors ◽  
Faroe Islands ◽  
Stock Identification ◽  
Relative Importance ◽  
Age Classes ◽  
Otolith Shape ◽  
Left And Right

The effects of sex, stock, and environment on the shape of known-age Atlantic cod (Gadus morhua) otoliths from the Faroe Islands were investigated. Moreover, the feasibility of otolith shape analysis for stock identification was evaluated. The shape was described by using several normalized Fourier descriptors and morphometric variables. There were no consistent differences between the left and right otoliths and between sexes within different age classes, stocks, and environments. With our experimental design, we could evaluate the relative importance of genetic and environmental conditions (water temperature and diet regime) on otolith shape and morphometrics. Using otolith shape, cod individuals were significantly separated into Bank and Plateau stocks. Total classification success was between 79% and 85% between stocks and between 85% and 96% between environments for the different age classes. The significant differences in otolith shape between Faroe Bank and Faroe Plateau cod stocks provided a phenotypic basis for stock separation. Stock and environmental influences were substantial in determining the shape of cod otoliths.

Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

1987 ◽  
Vol 44 (1) ◽  
pp. 14-25 ◽  
Author(s):  
L. J. Buckley ◽  
R. G. Lough
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Melanogrammus Aeglefinus ◽  
Good Growth ◽  
Georges Bank ◽  
Larval Population ◽  
Prey Biomass ◽  
Recent Growth ◽  
Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

Fish Catches and Long-Term Tidal Cycles in Northwest Atlantic Fisheries: A Nonlinear Regression Approach

1987 ◽  
Vol 44 (11) ◽  
pp. 1890-1897 ◽  
Author(s):  
Paul Cabilio ◽  
David L. DeWolfe ◽  
Graham R. Daborn
Keyword(s):  
New England ◽  
Nonlinear Regression ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Significant Negative Correlation ◽  
Clupea Harengus ◽  
Atlantic Menhaden ◽  
Melanogrammus Aeglefinus ◽  
Grand Banks

Selected long-term fisheries catch data from the New England – Fundy area and the Grand Banks were examined for concordance between changes in fish catches and the 18.6-yr nodal cycle of the tides using a nonlinear regression model. Significant positive correlations were found for Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), alewife (Alosa pseudoharengus), Atlantic herring (Clupea harengus harengus), and scallop (Placopecten magellanicus), with lag times that are biologically appropriate for the time from hatching to recruitment into the fishery. A significant negative correlation with the nodal cycle was evident for Atlantic menhaden (Brevoortia tyrannus), for which this area constitutes the most northerly part of its range. Cod catches on the Grand Banks showed no correlation with the nodal cycle. It is suggested that the correlations between the nodal cycle and the changes in fish catches are caused by correlated changes either in sea surface temperature or in productivity resulting from changes in the degree of vertical mixing.

scholarly journals Environmental DNA concentrations are correlated with regional biomass of Atlantic cod in oceanic waters

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ian Salter ◽  
Mourits Joensen ◽  
Regin Kristiansen ◽  
Petur Steingrund ◽  
Poul Vestergaard
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Environmental Dna ◽  
Sampling Effort ◽  
Trawl Survey ◽  
Catch Per Unit Effort ◽  
Fish Stocks ◽  
Powerful Approach ◽  
Commercially Important ◽  
Positive Correlations

AbstractEnvironmental DNA (eDNA) has emerged as a powerful approach for studying marine fisheries and has the potential to negate some of the drawbacks of trawl surveys. However, successful applications in oceanic waters have to date been largely focused on qualitative descriptions of species inventories. Here we conducted a quantitative eDNA survey of Atlantic cod (Gadus morhua) in oceanic waters and compared it with results obtained from a standardized demersal trawl survey. Detection of eDNA originating from Atlantic cod was highly concordant (80%) with trawl catches. We observed significantly positive correlations between the regional integrals of Atlantic cod biomass (kg) and eDNA quantities (copies) (R2 = 0.79, P = 0.003) and between sampling effort-normalised Catch Per Unit Effort (kg hr−1) and eDNA concentrations (copies L−1) (R2 = 0.71, P = 0.008). These findings extend the potential application of environmental DNA to regional biomass assessments of commercially important fish stocks in the ocean.

Partial Recruitment Considerations in Setting Catch Quotas

1993 ◽  
Vol 50 (4) ◽  
pp. 734-742 ◽  
Author(s):  
A. F. Sinclair
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Age Groups ◽  
Combined Effects ◽  
Total Allowable Catch ◽  
Catch Rates ◽  
Fishing Fleets ◽  
The Individual ◽  
Nova Scotian ◽  
Target Fishing

An approach is presented for investigating the interactions between fishing fleets that compete by exploiting different age-groups of the same resource population. The term "partial recruitment" (PR) is used to describe the age-specific exploitation pattern experienced by a population, either from individual fishing fleets or the combined effects of several fleets. Methods are presented to calculate catch quotas for the individual fleets if the management objective is to keep fleet effort constant, or alternatively to predict catch rates by fleet if the allocation rules are based on a percentage sharing of the total allowable catch (TAC) among fleets. Simulations based on an Atlantic cod (Gadus morhua) fishery on the Nova Scotian Shelf is used to illustrate the method. The results indicate the importance of considering differences in PR among competing fishing fleets when setting catch quotas. The relative effort exerted by the fleets will affect target fishing mortalities. The fleet that concentrates on younger fish can intercept recruitment. Since the fleets exploit different age-groups, changes in fishable biomass due to recruitment variation are lagged, and fishing success will vary among fleets. Understanding the dynamics of PR may help explain why certain fleets either exceed or fall short of catch quotas.

The influence of forage fish abundance on the aggregation of Gulf of Maine Atlantic cod (Gadus morhua) and their catchability in the fishery

2014 ◽  
Vol 71 (9) ◽  
pp. 1349-1362 ◽  
Author(s):  
David E. Richardson ◽  
Michael C. Palmer ◽  
Brian E. Smith
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Distribution Patterns ◽  
Fish Populations ◽  
Dependent Data ◽  
Forage Fish ◽  
Catch Per Unit Effort ◽  
Sand Lance ◽  
Unit Effort

Shifts in the distribution and aggregation patterns of exploited fish populations can affect the behavior and success of fishermen and can complicate the interpretation of fisheries-dependent data. Starting in 2006, coinciding with an increase in sand lance (Ammodytes spp.) abundance, Gulf of Maine Atlantic cod (Gadus morhua) concentrated on Stellwagen Bank, a small (405 km2) underwater plateau located in the southwestern portion of the larger (52 461 km2) stock area. The cod fishery in turn concentrated on Stellwagen Bank. Specifically, the proportion of Gulf of Maine cod landings caught in a single 10-minute square area (260 km2) encompassing the tip of Stellwagen Bank increased from 12% in 2005 to 45% in 2010. An increase in landings per unit effort in the fishery coincided with the concentration of the fleet on Stellwagen Bank. Overall, both fisheries-independent and fisheries-dependent data indicate that an increase in sand lance abundance resulted in cod aggregating in a small and predictable area where they were easily caught by the fishery. More broadly, this work illustrates how changes in the distribution patterns of fish and fisherman can decouple trends in abundance and fisheries catch per unit effort.

scholarly journals Fecundity estimation of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) of Georges Bank: Application of the autodiametric method

2009 ◽  
Vol 99 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Alexandre Alonso-Fernández ◽  
Ann Carole Vallejo ◽  
Fran Saborido-Rey ◽  
Hilario Murua ◽  
Edward A. Trippel
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Haddock Melanogrammus Aeglefinus
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