UKURAN CANGKANG, PERKEMBANGAN GONAD, DAN ‘SURVIVAL’ ABALON Haliotis varia, DI PESISIR TIMUR LIKUPANG

Abstract

Abalone is one of the invertebrates that live in coastal areas, where this area is a transitional area that has dynamic environmental conditions, which can affect the activities of biota that live on it. This study aims to determine the shell size, gonad maturity, and the survival of abalone, Haliotis varia, in the intertidal and subtidal zones. Five abalones were placed in a basket with a size of 25 X 20 X 10 cm with an opening cavity of 1 cm in diameter. This basket was placed on a concrete permanent in the intertidal and zubtidal zones. There were 3 baskets, as a replication, where each had abalone, where their length and weight were measured.  The baskets were placed in parallel position to the sea with 10 meters distanced among baskets. Brown algae, as food, weighing 10% of the total body weight of abalone/day, were included in each basket. Observations of the length, weight, gonads maturity and the number of abalone in each basket were carried out every month, from September – November 2019. The results show that a pattern of increasing shell length of abalone in the intertidal zone from September-November with the average sizes of 0.14 cm/month occurred. The pattern of increasing shell length from September – November for abalone placed in the subtidal zone with the average shell length of 0.24 cm/month was obtained. Statistical test using 2-Way Analysis of Variance, by first testing the normality of the data, where time and location as the main factors were applied. The results show that shell size was not significantly affected by time (P>0.05) and location (P>0.05). The pattern of increasing gonad development for abalone placed in both intertidal and subtidal zones from September to October was obtained. The gonad development decreased from October to November indicating spawning occurred. The percentage of survival abalone decreased from 100% in September, 60% in October, and 40% in November in the intertidal zone, and from 100% in September, 60% in October, and 47% in November in the zubtidal zone. A relative better survival abalone in the subtidal zone than in the intertidal zone occurred.  Factors affecting shell size, gonad development, and survival abalone in the intertidal and subtidal are discussed.  Key Words: Abalon, ukuran cangkang, gonad, survival, subtidal, dan intertidal.