How are Fishermen Changing the Genetics of the Ocean

A little while ago in my ecology of fishe course we discussed an interesting topic that has to do with both gentics and fisheries management. There are a great many fish that have been fished for a long time. Fishermen tend to fish for the biggest catch. The reason that this is such a problem, is that traditionally in certain species, there are a few genes that promote dwarfed sized fish. These dwarfed sized fish if mate with bigger fish will cause the resulting offspring to be much smaller than the big fish. Therfore as fishermen continue to overfish the big fish of different species, it is not only depleting the fish resource, but is caausing a shift in the allele frequencies of the dwarf fish genes in the population and thus the the trend observed in the oceans, are that there are not only far less fish available, but the majority of the fish are small. Just something to think about.

Coastal Barriers

There are three main types of coastal barriers that are formed. These include spits, barrier beaches, and barrier islands. All of these barriers are formed by similar processes, such as wave induced, tidal range, sea level rise, and fluvial sources. The only real fifference between the three structures has to do with the form of each. Spits are barriers that are attached to either the mainland or from and island (flying spits). One very local exmaple of a spit, is Buctouche spit, which is a great example for looking at the evolution of spits over time. The general premice, is that sediment is eroded from the proximal end (the end connected to land), this can include beach material as well as material from the dune. This sediment is then transported by longshore drift and is deposited on the distal end. As well a lot of sediment foes off shore and eventually is reworked to form new spits further down shore of the original. (Ollerhead and Davidson Arnott, 1995). Barrier islands are only really different from spits due to the fact that they are not connected to shore. This allows there to be many inlets in between barrier islands, which allow ocean water to move in to the back barrier environment. Barrier beaches are slightly different then bouth spits and barrier island in that they are completely made up of beach material and do not contain dunes. Therefore they are less protective structurs due to the absence of dunes. Barriers in general are very protective structures that protect lagon, ponds, salmarhes, and mangroves from intense wave and tide action that would normally occur along the coast. This allows for prime spawning grounds for many fish in these estuarine conditions as well as allows for the devlopment of larvae. Barriers unfortunately have been negatively effected by human greed, as dredging, building of causeways, and jetties have all caused changes to the system. Dredging which commonly occurs in the estuary hurts these fragile habitats as well as the reulting filling in of sediment for more recreational land changes the ecosystems present. Causeways can impede tidal flow and thus cause there to be a negative impact on the coasal geomorphology of barriers as well as on the biology that lives there. Things such a jetties cause the deposition of sediment in areas that it would normally not occur and thus can cause a negative sediment budget situation that may cause the continued erosion and eventual elimination of spits and the like, thus causing back shore areas to become exposed to natures whim.

Culinary Lab

Today in my Ecology of Fishes class we all had to bring a fish/invertebrate dish to share with the class. We also had to give a short presention on it. The dish that I prepared was Tuna pita pockets. I did a little bit of research to find out what species of Tuna it was(since they are all quite different), and found it to probably be the Skipjack Tuna. The reason I was able to decipher that this was the one, is from a number of things. First off the fact that it was really the only tuna species that tends to have pinkish meat was a huge clue. Secondly the fact that it is heavilly consumed in the United States was a further clue, as many Tuna species are only eaten in Japan. A third clue, was the fact that because it is the smallest tuna species, it is easy to make into chunks for canning purposes (which was what I used). These three things left me pretty certain that this was the Tuna species that I had made. one very important fact about this small Tuna (350mm long), is the fact that unlike other Tuna does not really impact Dolphins. The fact that it does not swin with Dolphins as many bigger Tuna species do almost guarantees that it be Delphin friendly (this was even on the package for the canned no name Tuna). A second interesting fact, is that this tuna is currently caught at 1.5 million metric tonnes per year and is probably the maximum that the world as an ecosystem can sustain and thus maked it a threatened species.

Some other important facts:
1) Most popular Tuna for consumption
2)Swims in upper layers of ocean
3)Highly migratory (found all over the worlds tropical waters)
4)Live on average about three years

Links:
1)http://www.atuna.com/species/species_datasheets.htm#Skipjack_tuna

Contaminants in an Arctic Shark

The only sharks found in the Arctic are so called sleep sharks. These include the Greenland shark which we heard about from the guest lecturer in Ocean Use and Management. These sharks are large (4-5 meters), and very slow moving. As we learned in class these sharks have been said to feed off of seals near sable island. They also feed off of flounders. There positioning in the Arctic food web was not known until very recently as they have not been very heavilly studied. Recent studies have shown thier tissue to contain a high level of organochlorine contamination. These are compounds that are long lasting pollutants and they concentrate as they move up the food web(bioaccumulation). What this means for the ecology of the species is that it is feeding at a high trophic level (fourth and fifth level). This is where the seals come in as they are at that trophic level. These sharks still tend to live a very long time, however the possible implications from the contaminents likely imapct tings such as reproduction and could have worst impacts in future generations.

Information found for this was from Fishes an introduction to Icthyology 5th edition, Peter Moyle.

Whale Sharks

The whale shark although imposing in size is a gentle, filter feeding animal. It is the largest known fish and for that reason alone it needs to be protected. This shark is found in tropical and warm temperate oceans (species range). It is both a pelagic species (feeding in open waters) and a benthic species feeding near the coasts.This shark has been found roaming about as far inland as estuaries and lagoons helping to show its great adaptablility to a multitude of habitats.This shark along with the megamouth and basking sharks is one of three known filter feeding shark species on Earth today. The Whale shark is commericially fished in many areas of the world and for that reason it is considered to be a vulnerable species.Although their enormous size Whale sharks are one of the most friendly creaturs in the sea and divers can play with these sharks with minimal risk of being injured. A magnificant species