Assignment #1 Ecology of My Fish Northern Pike (Esox lucis)




Дата канвертавання26.04.2016
Памер8.22 Kb.
Katie Twitchell

Lab: Wed @ 1:20



Assignment #1

Ecology of My Fish


Northern Pike (Esox lucis)

Article 1:

Smith, B., Farrell, J., Underwood, B., and Smith, S. 2007. Year-Class Formation of Upper St. Lawrence River Northern Pike. North American Journal of Fisheries Management 27: 481-491.

Q1. The factor identified in this paper as influencing the northern pike is the water temperature and water levels and the effects of these environmental conditions on the year-class strength.

Q2. According to the authors, they concluded that the water temperature has a positive correlation with high water temperatures during the fall, spring, and summer. These conditions produced strong year-classes. Temperature influences behavior and timing of spawning, early development, and the abundance of prey. In addition, it was concluded that a strong year-class is negatively correlated with water levels. This could potentially be due to not having access to ideal and suitable spawning grounds causing less success in survival and thus a weaker year-class.

Q3. In this article there were a few figures present. I found that in this paper the figures were not as useful as some figures in other articles. There were many data tables present but I found that the literature of the paper proved to be a better explanation on the data and the results than the figures.
Article 2:

Bystrom, P., Karlsson, J., Nilsson, P., Van Kooten, T., Ask, Jenny., and Olofsson, F. 2007. Substitution of top predators: effects of pike invasion in a sub arctic lake. Freshwater Biology 52: 1271-1280.

Q1. This paper focused on the cascading effects on the trophic levels in the sub arctic lake system that is being invaded by the northern pike.

Q2. With the warming climates the northern pike are able to invade habitats that were previous unsuitable to the pike. Compared to the pike, the native sub arctic species the Arctic char holds a similar spot in the tropic system as top predator. However, when compared in piscivory efficiency, the pike is more adapted and thus is more efficient in predation. This replacement will have a positive effect on the pike but create negative effects on the native fish of these sub arctic communities changing the ecosystem and lower trophic levels such as possibly eliminating the char, having a negative effect on the planktivorous fish such as the ninespined stickleback, thus having positive effects on the primary consumers such as zooplankton and benthic invertebrates.

Q3. There were many graphs and schematic charts that illustrated the many points of the paper. I found that a schematic trophic diagram was very helpful in understanding the ecosystem cycles. Also in this paper there were many helpful graphs that illustrated the data collected. I really liked that the graphs compared pike versus char data. It clearly showed that comparisons and was easy to interpret.
Whale Shark (Rhincodon typus)

Article 1:

Duffy, C. 2002. Distribution, seasonality, lengths, and feeding behaviour of whale sharks (Rhincodon typus) observed in New Zealand waters. New Zealand Journal of Marine and Freshwater Research 36: 565-570.

Q1. There were many environmental factors that were addressed as influencing the whale shark. These factors included location of sightings based on water temperature, season, and feeding habits.

Q2. It was found that the whale shark was sighted near outer shelf and shelf-break areas near Princes chain, Three Kings Island (34◦10’S) and between North Cape (34◦28’S) and Whale Island (37◦49’S) with seabed depths ranging from 50 to 490m with the mean being 155.9 m and the mode being 100m. The month in which most sightings were reported being February (55% of the sightings) although with increasing sightings around November through April. In addition, the sea surface temperature for the sightings ranging from 21 to 24 degrees Celsius. From these sightings the average length was 8.15 m with a range from 3.5 to 15 m. From this data it was concluded that the whale shark performs seasonal migrations to the New Zealand waters during their spring and summer months under these conditions.

Q3. There were two extremely helpful graphs in this paper that showed the number of sightings and in what month and another graph that illustrated the total length frequencies observed. There was also a helpful map that showed the sightings and their locations.
Article 2:

Wilson, S., Pauly, T., and Meekan, M. 2002. Distribution of zooplankton inferred from hydroacoustic backscatter data in coastal waters off Ningaloo Reef, Western Australia. Marine and Freshwater Research 53: 1005-1015.

Q1. This article demonstrates how the ecology of the whale shark is influenced by the distribution of zooplankton populations off the coast of Western Australia in the Ningaloo Reef.

Q2. From the data collected it was determined that the seasonal aggregation of whale sharks coincide with that of large zooplankton populations. There were consistently found to be congregations of whale sharks and devil rays (other planktivores) between March and June of each year near the outer barrier reef shelf front which is related to a seasonal peak in the zooplankton population.



Q3. There were numerous figures present in the paper. I found them helpful. They clearly illustrated the information gathered. Many of the figures were colored illustrations showing distributions or locations. They were all clearly labeled for interpretation and explained so that they could clearly be understood.


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