Dear Shannon,

I was working on clams, cockles or similar species (Venerupis, Cerastoderma, etc) more than 20 years ago…. My experience of assessment and management of these species is very dependent of the dynamic of each species. Some species such cockles have short life span (only two years and two cohorts are regularly present on the sand beds). In other cases such as some Venerupis, the life span could be also short, but in other Venerupis species 5 years or even more are present on the sand beds. In the first case a cohort tracking in biomass and (it is important in this species), the annual recruitment levels (regularly very fluctuant and affected by rains, etc.) and the condition factor (dry vs. wet products) in combination with the season of spawning-settlement, could by be good approaches for modeling.  In the second case of species, a similar approach is possible in some cases when cohorts are well identified over time.  Otherwise size-biomass models could be useful in combination with the other variables. Regards Jaime.

Shannon,

Have you looked at the DLMtool box in R?  It is pretty flexible.

Hi Tom and Jaime,

Thanks for your quick responses, and hello to both of you! It was nice to hear from friends! I certainly appreciate all your suggestions. I will continue to research these techniques. We are using the DLM toolbox now for finfish species in the Caribbean. We hope to expand its use to conch and lobster, but we haven't tried it yet. We've contracted one of the authors, Tom Carruthers, so I'm enthusiastic that he'll advise us well.

Thanks again!

Shannon

Estimada Shannon:

Cuando se impulsan nuevas pesquerías de invertebrados marinos frecuentemente se centran en especies para las cuales existe poca o muy limitada información tanto en los aspectos biológicos como de la explotación.

Para especies de invertebrados bentónicos de nula o escasa movilidad se recomiendan los esquemas RZP (Rotación de Zonas de Pesca), este esquema eco-sistémico trata de lograr el máximo rendimiento sustentable, dividiendo el área total de pesca en sub-áreas, preferentemente de igual abundancia, para que sean explotadas secuencialmente en el tiempo y permitir la recuperación del stock en las zonas no explotadas a través de la reproducción, crecimiento y reclutamiento. Anudado a lo anterior el manejo pesquero a través de un esquema RZP, constituye una estrategia precautoria, debido a que estos esquemas ayudan a mitigar los efectos de la sobrepesca del crecimiento y del reclutamiento.

Te recomiendo consigas el siguiente artículo: Caddy, J. F. (1993). Background concepts for a rotating harvesting strategy with particular reference to the Mediterranean red coral, Corallium rubrum. Marine Fisheries Review, 55(1), 10-18.

Espero te ayude mi respuesta. Saludos cordiales.

you can look at climax density figures for the same species in same ecosystems elsewhere, that are well or better studied, and derive an indication of where your species is currently located. if i am not mistaken, age/structure for lobsters is not possible because of a lacking biological tissue that "records" seasonal patterns - but this you have to check.

Adrian Hordyk and myself have been developing our Length-based assessment of spawning potential ratio for these types of situations. You just need representative size composition data for the exploited and adult part of the stock, estimates of the life history ratios (M/k & Lm/Linf.) synthesized from the literature for your species (or similar species) and a local estimates of size of maturity so that you can infer local Linf. You'll find the papers we've been publishing over the last couple of years about the technique on our profiles.

Thanks Jeremy, Gilles and Gracias Miguel! I appreciate all you suggestions.

Shannon