User:Krouskop.9/sandbox

Topic: Does over fishing have an impact on the genetic evolution of fish?

Pandolfi, J. (2009). Evolutionary impacts of fishing: Overfishing's ‘Darwinian debt’. F1000 Reports, 1(43). Retrieved September 14, 2014, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2924707/

The author of this paper is studying the impact of overfishing on the phenotypic traits of fish, even after the overfishing ceases to exist. He talks a lot about the differences in genetic responses to the exploitation and the environmental responses to the exploitation, and really helps the reader distinguish when to take each one into account for the changes.

Swain, D., Sinclair, A., & Hanson, M. (2007). Evolutionary response to size-selective mortality in an exploited fish population. Proceedings of the Royal Society, 274(1613). Retrieved September 14, 2014, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2924707/

The author focuses this paper on the consequences of exploiting fish based on the size of the fish. He studies the change in genetic growth rate due to the size-selection mortality rate of the population. His experiments show the correlation between size mortality in the parental generation and size of offspring.

Law, R. (2007). Fisheries-induced evolution: Present status and future directions. Marine Ecology Progress Series, 335, 271-277. Retrieved September 14, 2014, from http://floridarivers.ifas.ufl.edu/Carl Class/Carl Class II/MEPSLifeHistoryTheme.pdf#page=23

The author’s focus is on how rapidly fisheries are impacting evolutionary change. He states that phenotypic change of exploited fish does in fact exist; however, there is little evidence of selection differentials caused by exploitation. Also, evolution driven by fishing occurs at a considerable rate and is clearly observable.

Law, R. (2000). Fishing, selection, and phenotypic evolution. ICES Journal of Marine Science, 57, 659-668. Retrieved September 14, 2014, from http://icesjms.oxfordjournals.org/content/57/3/659.full.pdf html

This paper focuses on how fish exploitation impacts the size of a fish at a certain age and the age at which the fish matures. These changes in size and maturation can be due to genetic changes, but it may also be due to the spatial differences in population from the overfishing. Selective breeding in aquaculture shows us that when breeding for a specific trait there is a significant amount of genetic change, and overfishing could be causing this same type of mechanism to happen.

Hilborn, R., & Minte-Vera, C. (2008). Fisheries-Induced Changes in Growth Rates in Marine Fisheries: Are they Significant? Bulletin of Marine Science, 83(1), 95-105. Retrieved September 14, 2014, from http://www.ingentaconnect.com/content/umrsmas/bullmar/2008/00000083/00000001/art00006

The authors recognize the fact that overfishing does have an impact of the phenotypic traits of a fish population, but then they study if these impacts on traits are significant enough to make a long term difference in that population of fish. They show in their experiments that the effects commercial fisheries had on population in the wild had less of an impact than what scientist were finding in laboratory experiments.

Article web address: https://en.wikipedia.org/wiki/Oncorhynchus#Influence_of_overfishing

3 suggestions:

The following is regarding the section titled “Influence of overfishing”: This information is a bit out dated and could use some updating. I have found an article on pacific salmon published in 2008 that goes into detail about the incline of pacific salmon since the end of the 1980s. It could be very beneficial to the article to add these recent findings and studies, so your information is up to date and correctly informs the reader.

In the same article, they not only go into detail about the incline in population, but they also talk about the ongoing consequences that the original dramatic decline in the population have had on the present population. These consequences include different reproductive strategies, age of maturation, and average size of the salmon. Adding some of these details to the article would provide more evidence for the claim that “reduction of productivity in pacific salmon is, in part, seeded in the overfishing and has caused a reduction in population sizes throughout pacific salmon species”.

Another beneficial addition to this article could be to look at the reduction in body size from a positive viewpoint. One in particular that comes to mind is the benefit a smaller salmon could have in a body of water effected by global warming. Smaller salmon like to be in warmer water, so with the water temperature increasing, smaller body size could be a positive change for the population.

One sentence and citation:

Today, it seems that population numbers of pacific salmon are on the rise, however the consequences from the overfishing in the 70s and 80s are still being reflected with the average body size of salmon being smaller than before the event of overfishing.

Hard, J., Gross, M., Hilborn, R., Kope, R., Law, R., Reynolds, J., & Heino, M. (2008). Evolutionary consequences of fishing and their implications for salmon. Evolutionary Applications, 1(2). Retrieved September 30, 2014, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352430/

NEW ARTICLE CREATED For as long as the human population has existed, fishing has been an important tool for survival. There is no doubt that the exponential growth of the human population has had a detrimental effect to our resources on the planet. This can be attributed to the rate at which we are able to exploit our resources, with the help of modern techniques and technology. Fishing practices and equipment have become more advanced, which allows for non-random fishing and for more fish to be caught in a shorter amount of time.[1] Non-random fishing means that the fishermen are able to catch certain fish in preference to others. In order to not completely deplete the populations of fish, many people have felt the need to implement size-selective fishing, which is a type of non-random fishing. When practicing size-selective fishing, only those bigger than a predetermined size will be kept and the fish smaller than that specific size are supposed to be returned to their habitat. The initial, superficial thought behind size-selective fishing is that by returning the fish you are allowing the smaller, and likely less mature fish to continue to grow and reach maturity so they will have a chance to reproduce and keep the population numbers stable. However, this fishing technique may have a more complex impact on these populations of fish that might not be completely noticed until several generations have been exposed to this practice of fishing.[2] Much research has been done and shows evidence that size-selective fishing does indeed impact the fish populations for several generations, many times, even after this method of fishing ceases to be used on the population. The change in average size in a population is due to a mechanism called genetic drift, or allelic drift. To elaborate, when the mortality rate of bigger fish is increased due to size-selective fishing, then selection pressures are being generated on the population. There is selection working against the bigger fish, and selection working for the smaller fish, which leads to small body size being advantageous for the survival of the fish.[3] If smaller body sized fish are more likely to survive, then those individuals’ genes or alleles have a better chance of being passed on to the offspring generation, thus causing a selection differential between the average population size and the individual’s size that are chosen to reproduce. Therefore, the offspring generation is going to show a smaller body size on average because more genes or alleles for the small body size trait are phenotypically present in the population. The value of the selection differential depends on the strength of selection, but one must also take into consideration the amount of phenotypic variation within the population.[4] If there is high variation and strong selection the selection differential is going to be large. However if there is low variation, but still strong selection the selection differential is going to decrease to some degree. The size of a fish and the age at which a fish matures are typically correlated to each other. These traits are often called life history traits. So, since the body size is decreasing, the age at which maturation occurs is going to be lowered by a similar mechanism because the fish must reproduce before they reach that predetermined size that is acceptable for fishermen to keep. Over several generations of this induced selection by size-selective fishing, the population is likely to show evidence of phenotypic evolution, caused by this genetic or allelic drift. Furthermore, after size-selective fishing has been eliminated, the populations will continue to reflect the effects that the selection pressures implicated, and an increase in body size is rarely seen within a population after the elimination. [5]