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ToR 1: Explore and review availability of information and existing data on reproductive potential by areas and species
Co-Leaders: J. Tomkiewicz (Denmark) and J. Burnett (USA)

Two papers have been produced:

J. Tomkiewicz, M. J. Morgan, J. Burnett, F. Saborido-Rey

The availability of data to improve indices of stock reproductive potential was reviewed for 42 Northwest Atlantic groundfish stocks comprising gadoids, flatfishes, redfishes and grenadiers. For many of the stocks, information on population parameters such as stock size and size/age composition estimates exists for three or more decades. However, possibilities for estimating stock potential egg production are constrained by scarcity of fecundity data.

M. J. Morgan, J. Burnett, J. Tomkiewicz, F. Saborido-Rey

Information was collected on the availability of data to estimate reproductive potential on fish stocks in the north Atlantic. Information was collected on a total of 53 stocks or stock complexes from both the Northeast and Northwest Atlantic. A series of tables were compiled that provide an overview of the availability of basic information, evaluate the quality of the information and provide references to this information.

ToR 2: Explore possibilities to develop standard internationally coordinated research protocols to estimate egg and larval production
Co-Leaders: H. Murua (Spain) and A. Thorsen (Norway)

Five papers have been produced:

H. Murua and F. Saborido-Rey

This contribution describes and identifies the most common reproductive strategies of a large number of commercially important fish species of the North Atlantic with regard to oocyte development, ovary organization, recruitment of oocytes, and spawning pattern. Categorization of species according to reproductive strategy assists in the estimation of species-specific fecundity and reproductive potential using various developed protocols.

H. Murua, G. Kraus, F. Saborido-Rey, P. R. Witthames, A. Thorsen, S. Junquera

Appraisal of reproductive strategy and fecundity is necessary to evaluate the reproductive potential of individual fish species. The advantages and disadvantages of each method currently used to estimate fecundity of wild collected fish are provided.

A. Thorsen, E. A. Trippel, and Y. Lambert

We review and recommend a variety of methods used to conduct experiments on estimating egg production of marine fishes in the laboratory. Aspects assessed include domestication of wild fish, holding facilities and handling, broodstock diet, tagging of fish, monitoring maturation, feeding during spawning, spawning conditions, egg collection techniques, spawning fish and stress, artificial fertilization, initial egg sample analysis, and egg and larval quality and mortality.

Y. Lambert and A. Thorsen

Experimental work on the reproduction of captive marine fish species provides the opportunity to improve our knowledge of the factors and mechanisms regulating reproduction of fish populations in natural environments. The integration of captive and wild studies can potentially be used to predict changes in the reproductive characteristics of fish populations in response to variations in specific environmental conditions in the wild. This dual approach can also be used to develop predictive models incorporating biological and environmental factors.

E. A. Trippel

Experimental techniques used to evaluate male reproductive potential of gadoid, pleuronectoid and clupeid fishes were reviewed. Aspects examined include spermatogenesis, sperm density, sperm motility, fertilization potential, and the effects of sire on maternal reproductive success. An equation for determinate spawners is described that quantifies a population’s viable sperm production using data on adult body characteristics and associated quantity and quality of sperm. The equation was used to establish time series of viable sperm production for Atlantic cod (Gadus morhua) of Newfoundland and Labrador which was regressed against recruitment.

ToR 3: Explore and evaluate alternative methods to estimate reproductive potential annually or part of routine in monitoring and sampling schemes (such as HSI)
Co-Leaders: H. Murua (Spain) and A. Thorsen (Norway)

One paper has been produced:

Y. Lambert, N. A. Yaragina, G. Kraus, G. Marteinsdottir, and P. J. Wright

This review, largely based on gadoid fish species, indicates that relationships between indices of nutritional condition (e.g., condition factor, liver index) and potential fecundity meet the criteria of predictability and low effort and thus are candidate proxies for measuring egg production. No relationship examined was a suitable proxy for egg/larval viability and age and size at maturity. The development of alternative measures of reproductive characteristics of fish could result in more precise estimates of reproductive potential of fish stocks that could be used for hindcasting and predicting egg and/or larval production and viability.

ToR 4: Review possibilities to develop methods and opportunities to estimate stock reproductive potential for assessment and management
Co-Leaders: T. Marshall (Norway) and G. Marteinsdottir (Iceland)

Two papers have been produced:

C. T. Marshall, L. O’Brien, J. Tomkiewicz, G. Marteinsdottir, M. J. Morgan, F. Saborido-Rey, F.W. Köster, J. L. Blanchard, D. H. Secor, G. Kraus, Peter J. Wright, N. V. Mukhina, and H. Björnsson

There is accumulating evidence to suggest that spawning stock biomass (SSB) may not be directly proportional to reproductive potential. In this review, nine stocks illustrate the range of approaches that are being taken to developing alternative indices of reproductive potential from existing data resources. Management protocols should be adapted to incorporate the detailed information on reproductive potential that is increasingly becoming available rather than being restricted to approaches that have been designed for data-poor situations.

L. O’Brien, P. Rago, P. Berrien, and R.G. Lough

There is accumulating evidence to suggest that spawning stock biomass (SSB) may not be directly proportional to reproductive potential. In this review, nine stocks illustrate the range of approaches that are being taken to developing alternative indices of reproductive potential from existing data resources. Management protocols should be adapted to incorporate the detailed information on reproductive potential that is increasingly becoming available rather than being restricted to approaches that have been designed for data-poor situations.