Atlantic Cod : Evolutionary Selection For Small Bodied Fish And Recovery Of Fisheries

The discoverer of the titanic, Dr Robert Ballard famously referred to the deep sea as ‘far more alien than going to mars or the moon.’ The deep sea is one of the largest virtually unexplored ecosystems on the planet; it is found at a depth of 1000 fathoms [1] and is subject to adverse changes in temperature, pressure and light penetration amongst other factors. Therefore as expected fish decrease in abundance, and species diversity. This trend is prominent as in order to survive the harsh conditions of the deep sea, fish need a number of specific adaptations. Allowing them to ultimately survive, feed, and reproduce.

Black sea bass are fairly stout-bodied fish, with a long dorsal fin, and large pectoral and pelvic fins. The rounded tail sometimes has a long streamer trailing out from the top edge. Each gill cover has a flat spine near the outer edge. Mature males have a fleshy dorsal hump just anterior to the dorsal fin. The background color of the black sea bass (smokey gray, brown, or bluish black) is marked with darker patches and light speckles. The belly is only slightly lighter than the sides. Young sea bass are green or brown with a dark lateral stripe running from the head to the tail. Juvenile and adult black sea bass feed upon a variety of benthic invertebrates such as rock crabs, hermit crabs, squids, and razor clams. Black sea bass adults typically

When the words spread about the large size of fishery, fleets from all over the world joined the hunt. Every year, the size of the fleets got bigger and every year, the size of the catch increased. In the late 50s the arrival of large factor ships from other countries hailed the first onslaught to the finely balanced renewable cod fishery. These factory trawlers came from England, the U.S., the Soviet Union, East and West Germany, Portugal, Poland, and some Asia nations such as Japan and Korea. Towards the end of the 20th century, over 3

This efficiency is further increased in the late 1800s with government subsidy programs. Governments such as the American and French government started to give fisherman money so that they could purchase new equipment and larger boats (Parsons, 1993). This only further fueled the decline of the cod fishery. The end of the late 1800s marked the beginning of people starting to become concerned enough about the declining codfish populations to actually want to learn about what is

Without the moratorium, the cod population would have gone extinct and led to several losses. Despite the moratorium, the cod species is still considered as endangered in 2012. However, the trend of cod population has started to finally return after 20 years

The south pacific is well known for their upwelling especially around the coast of Peru and it is well known for its high productivity around the world’s oceans and supports a great deal of sea food around the world. However, the region is also known for its fluctuation in the fish stocks due to many biotic and abiotic factors (Figure 1) (Cury, Roy, and Faure 1998; Sandweiss et al. 2004).

A steady decrease in whale populations can have a top-down effect on many other species in the ecosystem, especially penguin, seal, and krill. The reasoning is because whales are a keystone species in the Southern Ocean (Ainley,

In 1989, the Canadian government revises assessment recommends and they reduce the capacity of fishery on 50%, but the government reduced to 200,000 tons with the finality of conserved cod stocks in 1990. That happened, because of scientific advices of DFO, that caused plants closures and 1800 employers loss their job. They work on 45% of capacity and the minister did not reaction about the problem. In 1992, the government decided to no more fishing for 2years moratorium. This left 40,000 unemployed and factories, plants closures. All groups were affected by over fishing.

The discovery of the effect of the ETP tuna fishery on dolphins has opened the door to a realization that other fisheries are killing several other marine mammals. The baji Lipotes vexillifer is now declared extinct as well as the vaquita Phocoena sinus. The Baji is a Chinese river dolphin and its extinction is caused by fishing lines; it is a long line of sharp hooks used for other fish but since it is used in the same Chinese river than the Baji, it catches and kills

One of these commonly arising problems is that single-species fisheries skew the age structure of the harvested populations by selecting for the largest and, thus, oldest individuals to maximize biomass harvested. This can result in several damaging effects on the population depending on the species its life history. The underlying cause is that fisheries often make the assumption that all eggs are equal, despite a large and growing amount of evidence to the contrary (Beverton and Holt 1957). Several studies have concluded that, in many fish species, the eggs of larger fish tend to be larger (Nikolsky 1953) and more nutritious which increases larval survival and later reproductive success. This was described in Pacific Rockfish by means of

Another famous fish is the herring. Herring move in large schools in shallow waters like rivers. They provide most of the food for Cape breton due to the large population of this species of fish. Herring are rapidly decreasing every month and are soon to be endangered. The most common herring to Cape Breton are the Alewife Herring which travel in large numbers of schools. Herring are beautiful fish that are a sight to see if you come and visit.

If the arctic becomes an area that is “open for business” for anyone to mine, drill or fish in it is likely that the habitats of many different species of wildlife will be damaged. Oil spills can severely hurt many species of bird and fish which live in the Arctic, as well as the animals which prey on them, and as there is currently no surefire way to fix or contain an underwater oil spill if it happens, along with the limited infrastructure currently in the Arctic, the results of one could be disastrous for the Arctic’s ecosystem. Over half of all of the United State’s fish supply comes from the Arctic Many areas of the Arctic already are being hurt by illegal fishing and unprofitable overfishing, which could be curbed if major countries would stop providing subsidies to unprofitable fishing

Overfishing significantly impacts biodiversity within ecosystems. Marine life imbalance is produced when fishing of top predators disrupts communities within the

Human Consumption and Commercial Fishing have led to a depletion of Cod stocks, specifically, the Atlantic Cod in the North Atlantic Region. The ecological, social and economic implications this has on society is not only evident today, but poses long-term consequences as well. Wicked problems are characterized by social complexity. (stakeholders, incomplete contradiction knowledge, opinions etc.) (Kolko, 2012) this issue may be considered a wicked problem because the Atlantic cod remain a demand in human consumption and the commercial exploitation remains a factor in the depletion of their stocks.

Currently, controversy exists over the response controlling this size trend; microevolution or phenotypic plasticity. Microevolution is a genetic change within a species in which size selective harvesting creates an artificial selection pressure. Individuals maturing at a smaller size have more opportunity to reproduce before capture, conveying a higher fitness under exploited conditions7. Phenotypic plasticity states instead that an individual’s genes can produce different phenotypes, observable characteristics, across an environmental gradient8 with no genetic change. Fishing mortality simply reduces population density: individuals can access more food and thus mature at a smaller size9. Unlike microevolution, plasticity is unviable as a long term resolution10. However, the selection pressure of size-selective fishing may cause the loss of the genetic variation required for species to recover and adapt to future scenarios6. As the effects of both responses are challenging to disentangle11, the debate on which is occurring remains controversial. Few studies have conclusively demonstrated a genetic cause12. Methodologies claiming to isolate evolutionary trends support microevolution though plasticity effects have yet to be fully eliminated, while rapid recovery of size when exploitation ceases suggests a plastic response. With fishery yield heavily impacted by life history traits, and size-selective harvesting mandated by minimum