Sustaining a thriving lobster fishery through science and community.
| Table of Contents
What's in a name?
Molting & Growth
Nervous & Sensory Systems
Muscular System & The Lobster's Tail
Larvae & PostLarvae
The Lobster's Future
Because of their tremendous commercial importance throughout the world, aquaculture of lobsters has been a dream for nearly a century. However, numerous difficulties have made these efforts unrealistic. Of the worlds lobsters, the clawed variety have the simplest early life history. Therefore, most aquaculture efforts have focused on them. Egg-bearing females are relatively easy to obtain and to hold in artificial settings. Hatching of the larvae is also easy and with the development of special holding tanks, called "kreisels", that spin the larvae around in circles (thereby preventing contact with each other and the resultant cannibalism that occurs with contact), so that rearing of larvae is simple and yields survival rates of around 70-80%. By manipulating water temperatures, it is possible to rear the larvae through all three larval stages and into the postlarval stage in less than a month. However, at this point, the postlarvae are strong swimmers and will rapidly cannibalize each other unless separated. But due to their small size, separation of individuals into small chambers is not particularly difficult. However, as the lobster grows, it must be transferred into larger and larger chambers and eventually this proves inefficient both in terms of space and water usage. While a legally sized lobster can be reared in approximately 2 years (as opposed to waiting 6-10 years in nature), the cost of space, water, and food is higher than the market price of the pot-fished lobster. Thus, it is currently more practical to make sure that the wild lobster population remains healthy and well-managed. Besides, wild, free ranging, slow growing, cold-water lobsters taste better.
Nonetheless, because of overfishing of some clawed lobster stocks, particularly in Great Britain and northern Europe, culturing and release of lobsters is being used to restock former lobster grounds. Lobsters are reared past the postlarval stage to a size of about 12 mm carapace length. They are then taken to suitable habitats by divers and released directly on the bottom. Tagging studies of these lobsters indicate that they are recaptured at a rate of about 5-7%, which is a higher survival rate than originally expected. It is hoped that over a period of time, these hatchery-reared animals will replenish the once-rich lobster grounds. It is important to remember, however, that this drastic measure has been taken only after lobster populations have crashed. We do not know whether these hatchery-reared lobsters behave similarly to their wild counterparts, nor do we know if they compete with their wild cousins for space and food. Release of such hatchery-reared juveniles should not be considered as a panacea for bad management practices - - instead, both fishers and managers need to work together to ensure that these radical measures need not be taken in the U.S. fishery.
of our efforts will come to naught if we continue to treat our coastal
areas as dumping grounds for pollutants. Lobsters bioaccumulate various
pollutants (PCBs, PAHs, dioxins, heavy metals, etc.) in lipid (fat) rich
tissues - - these are the midgut gland (the hepatopancreas or
"tomally") and the eggs. While their molt cycle helps rid them
of these pollutants with every molt, it is unknown what long-term effects
these pollutants have on the overall health of the lobsters or on the
development of the embryos and the survival of the offspring. More and
more of the catch landed in highly populated areas shows evidence of disease
previously unreported for lobsters, who are relatively disease-free animals.
These diseases include shell rot or shell burn (dark holes burned into
the shell). In addition to threats of disease and pollution, all studies
thus far indicate that the nursery grounds of all species of lobsters
occur nearshore along coastal regions, which humans impact dramatically.
Development of coastal areas, with the resultant sewage and pollution,
could dramatically impact the ability of the lobster to survive in the
kinds of numbers necessary to support current fishering pressures. The
lobster is not only a tasty treat, but is proving to be an important model
for many processes important to humans: they are used as neural circuit
models, models of hormonally-induced aggression, and are used to better
understand the aging process of muscles. Efforts are even underway to
make underwater mine-seeking robots based on a lobster walking model.
Such robots have already been produced based on crab walking models. Who
knows what other surprises the lobster has in store for us, if only we
manage to preserve them and conserve their habitats?
For further information, we suggest that the reader examine the following books:
Information provided by Kari L. Lavalli, Diane F. Cowan, and Diana Barshaw. Some material from an article in Hebrew, entitled "Lobsters: And Not Just on the Plate" in Teva Hadvareem, Volume 20, 1997 by Kari L. Lavalli.
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