There were second age-readers who looked at the otolith annuli to get a correct and efficient age. Both the reader’s disparities were resolved and corrected. The National Marine Fisheries Service examined ovaries and age structures of the female darkblotched rockfish from a collected in 2011 and 2012 to see the oocyte development stage and maturity. The length and age were estimated to be 30 cm length and 6 years this showed a 12 and 29 % decrease to the length and age of at 50 % maturity previously reported back from 1986 to 1987. This tells us that a shift to lower age maturity may be predictable to increase the rebuilding rate of a population after the end of overfishing this is not always the case.
In his essay Marine Parks, he puts forth the argument that marine parks should be closed down because observing marine animals is much better in the wild instead of being held captive in the marine parks. He states that the research conducted on these marine animals is not reliable, also that visits from foreign tourists will not decline with the demise of these parks. Moreover, he adds that such parks are unnecessary and cruel to these marine mammals. Bill Daly has a strong viewpoint on the reasons he gives for his argument, however, I do not agree with him. Indeed some of his reasoning does make sense, but according to me his reasons seem very theoretical or rather hypothetical and not applicable in the real world.
Sharks are much more useful when kept alive, and can be beneficial for several years; however, once they are dead there are no more benefits to be reaped besides what is originally obtained. The decrease in sharks can also be detrimental to many fisheries. Sharks feed on other carnivores down the food chain. Carnivores that sharks prey on often prey on creatures such as shellfish. Without sharks, there would be an increase in several other carnivores, leading to a vast decrease in the amount of shellfish and other herbivores in the sea, which can be detrimental to local fisheries.
(Chapperon et al. Laurent 2011) So, we added another variable. We wanted to see if it We predict that the larger the population and the higher the temperature, the movement there will be within that trial. In these four experiments we determine the effects water temperatures has on snails and longevity for the snails to separate from each other in larger groups. Methods Four experiments were conducted to determine how fast snails would move in 1 minute at different temperatures based on their population size.
As a result, the food chain is disrupted because the producers at the bottom of the food chain cannot produce because sunlight is blocked, leading the primary consumers without a source of food. This may even lead to primary consumers to eat plastic. Also, research shows that fish cannot detect these dead zones so once they enter them they most likely will not get out. In addition to this, contaminated fish and marine life humans consume can contribute to diseases and problems within the human body. Exposition to chemicals such as chemicals in plastic bottles and pesticides can cause hormonal problems, reproductive problems, nervous system damage and kidney damage.
With that predicted to increase to 99 percent by 2050” (“Ocean Plastic Pollution”). Another similar case states that “Hundreds of thousands of seabirds ingest plastic each year...Nearly all Laysan Albatross chicks -97.5 percent - have plastics pieces in their stomachs” (“Ocean Plastic Pollution”). The next well known animal affected by ocean pollution is fish. “Fish in the North Pacific ingest 12,000 to 24,000 tons of plastic each year” (“Ocean Plastic Pollution”). When fish consume the plastic, it will move up the food chain and affect other aquatic animals that consume fish.
Osmoregulators are able to control the movement of solutes whether it is internal or external. Osmoconformers do not have this ability and are isosmotic with their surroundings. Marine stars are stenohaline, animals who cannot withstand changes in the external osmolarity. So if a sea star has a sudden influx of water, the cells within will shrink or shrivel causing their organelles and cell membranes to be damaged and eventually die. Osmoconformers are not able to regulate solutes in their body in different concentration because of the permeability of their bodies and the absence of organs such as kidneys that allow them to produce urine in multiple solute
It is strongly recommended to avoid those activation to protect stream environment for eel natural habitat. (17) Thus, in light of the results in this study, it can be assumed that excavation and habitat destruction observed in recent years has probably reduced the quantity and quality of suitable habitats for juvenile eel, which could be negatively affecting both ecologically and economically. 4.5 Further studies Various observations European eel life history should be describe not as truly catadromous, but "facultative or semi catadromous". Due to fact that European eel were found in different waters such as freshwater,brakish and coastal,and freshwater phase is not be a essential part of their life history, could not make them not truly catadromous species. (18) This is the only experimental study until now, as far as we know, that contribute to the understanding the habitat choice of eel juveniles in brackish salinity water .Therefore further studies should be taken in order to contribute better understand about substrate selection in all Anguillae group.
When a species population is reduced in size, it loses the rare alleles needed to make its species thrive in future generations (Primack), the loss or decline in the genotypes of a species creates weak offspring. Expanding on the population bottleneck we have the founder effect that is occurring, as populations become small and smaller we leave a select few to carry on the population through their breeding effects. Population bottlenecks have more of a pronounced effect when populations are reduced below ten individuals for several generations (Primack). Bottlenecks caused by catastrophic events or periods may have a rapid change in population, but species can overcome this bottleneck in future generations. The reason, in a rapid or mass removal of a species those that remain, have not suffered from genetic drifting or loss of alleles and those small in number the species remains strong.