Gülnur METİN, Akın Türker İLKYAZ, Hasan Tuncay KINACIGİL

Orta Ege Denizi Tavuk Bal›¤› (Trisopterus minutus Linn., 1758)’n›n Büyüme, Ölüm ve Üreme Özellikleri

Trol çekimleri ile 1.527 adet tavuk bal›¤› (Trisopterus minutus Linn., 1758) Nisan 2001 ile Mart 2002 tarihleri aras›nda ‹zmir Körfezi’nden (Orta Ege Denizi) örneklenmifltir. Örneklenen bireylerin total boylar›n›n 10,6 cm (minimum, Eylül) ile 24,8 cm (Nisan) aras›nda da¤›l›m gösterdi¤i gözlenmifltir. Bireylerin %53’ünün erkek, %41’inin difli ve %6’s›n›n efleysel olgunlu¤a ulaflmam›fl bireylerden olufltu¤u tespit edilmifltir. Stokdaki difli:erkek oran›n›n 1:1,3 oldu¤u ve bireylerin I-V yafllar› aras›ndaki da¤›l›m gösterdi¤i gözlenmifltir. Von Bertalanffy büyüme parametreleri; L∞ = 28,1 cm, W∞ = 254,0 gr, K = 0,26 y›l–1 ve to = –1,52 y›l olarak hesaplanm›flt›r. Diflilerde ilk üreme boyunun 13,3 cm, erkeklerde ise bu boyun 12,5 cm oldu¤u bulunmufltur. Yumurtlaman›n Aral›k ay›nda bafllad›¤›, Ocak ay›nda maksimum seviyeye ulaflt›¤› ve Nisan ay›na kadar sürdü¤ü gözlenmifltir. Yumurta verimlili¤inin 1,236 ile 21,463 yumurta/difli aras›nda oldu¤u ve bu verimin bal›k boyu ve a¤›rl›¤› ile iliflkili oldu¤u tespit edilmifltir. Stoktaki toplam (Z), do¤al (M) ve bal›kç›l›ktan gelen ölüm (F) ile sömürülme oranlar› (E) s›ras› ile Z = 0,82, M = 0,38, F = 0,44 ve E = 0,57 y›l–1 olarak hesaplanm›flt›r. Elde edilen bilgiler ›fl›¤›nda, tür için minimum avlama boyunun 14 cm, av sezon yasa¤›n›n Ocak ile Nisan aylar› aras›nda olmas› önerilmektedir. Sömürülme oran› dikkate al›nd›¤›nda, stok üzerindeki av bask›s›n›n normalin biraz üzerinde gerçekleflti¤i gözlenmektedir.

Anahtar Kelimeler:

Trisopterus minutus, yaş, büyüme, ölüm, üreme, cinsi olgunluk boyu, Orta Ege Denizi

Growth, Mortality, and Reproduction of Poor Cod (Trisopterus minutus Linn., 1758) in the Central Aegean Sea

A total of 1527 of poor cod (Trisopterus minutus Linn., 1758) were collected by trawl hauls between April 2001 and March 2002 from İzmir Bay (central Aegean Sea). The size of the fish (total length) ranged from 10.6 cm (minimum, September) and 24.8 cm (April). The population was composed of 53% males, 41% females, and 6% immature individuals, with a female to male ratio of 1:1.3. The age composition of the samples was from I to V. The von Bertalanffy growth parameters were L\infinity = 28.1 cm, W\infinity = 254.0 g, K = 0.26 y-1, and to = -1.52 y. The length at first sexual maturity was 13.3 cm in females and 12.5 cm in males. Spawning season begins in December and reaches its maximum level in January while continuing April. Fecundity ranged from 1236 to 21,463 eggs/female and showed significant correlation with fish length and weight. The total (Z), natural (M), and fishing mortality (F) rates, and the exploitation ratio (E) for all individuals were estimated respectively as Z = 0.82, M = 0.38, F = 0.44, and E = 0.57 y-1. This shows that the poor cod smaller than 14 cm must not be harvested and fishing should be prohibited from January to April and that the poor cod stock in the central Aegan Sea is being exploited at a slightly higher than the optimal level.

Keywords:

Trisopterus minutus, age, growth, mortality, reproduction, sexual maturity length, central Aegean Sea,

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