Population dynamics of Japanese pink salmon (Oncorhynchus gorbuscha): are recent increases explained by hatchery programs or climatic variations?

2006 ◽  
Vol 63 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Kentaro Morita ◽  
Shoko H Morita ◽  
Masa-aki Fukuwaka
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Climatic Factors ◽  
Pink Salmon ◽  
Climatic Variation ◽  
Oncorhynchus Gorbuscha ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Climatic Variations ◽  
Mass Release ◽  
Effects Of Density

Hatchery programs involving the mass release of artificially propagated fishes have been implemented worldwide. However, few studies have assessed whether hatchery programs actually increase the net population growth of the target species after accounting for the effects of density dependence and climatic variation. We examined the combined effects of density dependence, climatic variation, and hatchery release on the population dynamics of Japanese pink salmon (Oncorhynchus gorbuscha) from 1969 to 2003. The population trends were more closely linked to climatic factors than to the intensity of the hatchery programs. The estimated contributions of hatchery-released fry to catches during the past decade are small. We concluded that the recent catch increases of Japanese pink salmon could be largely explained by climate change, with increased hatchery releases having little effect.

Incidence and Effects of Sea Lamprey (Petromyzon marinus) Parasitism on Breeding Pink Salmon (Oncorhynchus gorbuscha) from the Carp River, Eastern Lake Superior

1987 ◽  
Vol 44 (9) ◽  
pp. 1562-1567 ◽  
Author(s):  
Douglas B. Noltie
Keyword(s):  
Population Dynamics ◽  
Great Lakes ◽  
Negative Impact ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Pink Salmon ◽  
Reproductive Potential ◽  
Sea Lamprey ◽  
Oncorhynchus Gorbuscha ◽  
Pink Salmon Oncorhynchus Gorbuscha

The potentially important effect of Great Lakes pink salmon (Oncorhynchus gorbuscha) numbers on the population dynamics of parasitic sea lamprey (Petromyzon marinus) has thus far remained unassessed. This study reveals that despite their small size, pink salmon from the Carp River, eastern Lake Superior, sustain parasitism at rates and in body locations similar to other Great Lakes salmonids. In general, the incidence of sea lamprey parasitism increased with salmon length. Differences in marking rates between male and female salmon were attributable to their dimorphism in size: female pink salmon grew slower than males and bore more fresh wounds than males when sampled. Lamprey attacked fish of similar sizes in 1983 and 1984, but smaller ones in 1985. This parasitism had a negative impact on host breeding potential: marked fish were in poorer condition than unmarked ones. Marked males invested less biomass in gonad than did unmarked males, and wounded males occupied the spawning grounds for less time, thus reducing their reproductive potential. These results indicate that the population dynamics of both species may be determined in part by their mutual interaction.

scholarly journals Effects of density dependence and climatic factors on population dynamics of Cricetulus barabensis: a 25-year field study

2020 ◽  
Vol 101 (2) ◽  
pp. 507-514
Author(s):  
Ling-Ying Shuai ◽  
Li-Qing Wang ◽  
Yu-Ping Yang ◽  
Fu-Shun Zhang
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Large Scale ◽  
Population Change ◽  
Climatic Factors ◽  
Southern Oscillation ◽  
Keystone Species ◽  
Northern China ◽  
Human Beings ◽  
Effects Of Density

Abstract Rodents often act as keystone species in communities and play important roles in shaping structures and functions of many ecosystems. Understanding the underlying mechanisms of population fluctuation in rodents is therefore of great interest. Using the data from a 25-year field survey carried out in Inner Mongolia, China, we explored the effects of density dependence, local climatic factors, and a large-scale climatic perturbation (El Niño–Southern Oscillation) on the population dynamics of the striped hamster (Cricetulus barabensis), a rodent widely distributed in northern China. We detected a strong negative density-dependent effect on the population dynamics of C. barabensis. Rainfall had a significant positive effect on population change with a 1-year lag. The pregnancy rate of C. barabensis was negatively affected by the annual mean temperature in the current year, but positively associated with the population density in the current year and the annual Southern Oscillation Index in the previous year. Moving-window analyses suggested that, with a window length of 12 years, there was a significant interaction between rainfall and density dependence, with increasing rainfall alleviating the negative effect of density dependence. As C. barabensis often causes agricultural damage and can transmit zoonotic diseases to human beings, our results also have implications for pest and disease control.

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