| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 100 === In order to increase the population size of the Formosan landlocked salmon Oncorhynchus masou formosanus , the efforts rehabitating of this fish to the historic watershed had been excuted ever since 2006. A total of 900 fish had been released to Lo-Ye-Wei creek,Gon-gamin creek(Su-Jie-Lan upstream branch I) and Gon-bkuli creek from June 2009 to May 2011.
There had been no further observed survived fish of the 2007 year class (2007ycr, released in 2009) in both Lo-Ye-Wei creek and Su-Jie-Lan creek indicated the maximum age in the wild is less than 4. Fish population structure of fish in Lo-Ye-Wei creek had reached a stabilized society with a percentage of 2+ (2009 wild born (2009ycw), 21 % ; 2010 released (2009ycr), 14 %) and 1+ (2010 wild born (2010ycw), 31 %) and 0+ (2011 wild born (2011ycw), 34 %) upon the total number of 680 fish censused in April 2012. But the fish population either release in Gon-bkuli or in Gon-gamin of the Se-Je-Lan creek seemed not able to construct an effective size of population with various age groups in the wild.
Factorial responses of specific growth rate (SGR) and condition factor (CF) were analyzed according to the four main factors, fish origin (w, r, h), site (Ha, L, S ), growth season (L,H) and age (0+, 1+, 2+).
The averged SGR values told the genenal conclusions of the four main effect described below. It was found that fish grow fastest in hatchery, followed by the wild born fish and the released fish group, the slowest. Fish grew faster a during high temperature season than low temperture season. Fish grew faster in hatchery than in Lo-Ye-Wei creek and those in Se-Je-Lan creek grew the slowest. However, there were interaction among factors which might well reffect the background of the habitat conditions where the fish dwelt.
The physical (water volume) carry capacity (natural food supply factor not consedered) was estimated 350 kg (dry season) - 600 kg (wet season) mass in the 1.5 km investigation section of Lo-Ye-Wei creek.
|
|---|
