FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

We compared the larval survival rates of the F1 generations of six small abalone strains in Taiwan, including two inbred farmed strains from Ilan (YA and YB), two inbred wild strains from Taitung (TTA and TTB), one inbred farmed strain from Tainan (TN) and a hybrid crossing of farmed strains from Tainan and Keelung (TNP). While the YB, TTA and TTB strains had larval survival rates of more than 90% and the YA strain had an 82% larval survival rate, the TN and TNK strains had the lowest larval survival rates at 67.5% and 70.5%, respectively, after 34 days. Thus, we decided to study the genetic relationship between the strains with the highest (TTB) and lowest (TN) larval survival rates using random amplified polymorphic DNA (RAPD). Our results showed that the allelic diversity of the TTB strain was higher than that of the TN strain. Therefore, we further studied the growth and survival rates using another hybrid of small abalone. We cross-bred small abalone from three different sources in Taiwan: strain 1, a hybrid crossing of a female farmed strain with wild strains; strain 2, an inbred farmed strain; and strain 3, a hybrid crossing of a female wild strain with a male farmed strain. We compared the growth rates for each strain for an 8-month period starting at 3 months of age. The initial and final shell lengths for each strain were as follows: 22.13 ± 5.7mm to 36.26 ± 5.77mm for strain 1, 14.17 ± 3.9mm to 33.06 ± 4.13mm for strain 2, and 13.25 ± 2.9mm to 31.73 ± 3.54mm for strain 3. The survival rates within this 8-month period were 97% for strain 1, 83% for strain 2, and 98% for strain 3. Overall, strain 1 had the best growth and survival rates, followed by strain 3 and strain 2. In summary, our results indicate that cross-breeding can increase the genetic diversity and improve the growth and survival rates of small abalone.