Population dynamics of the African river prawn, Macrobrachium vollenhovenii, in Dawhenya impoundment

Gana’da Dawhenya göletinden Afrika nehri karidesinin, Macrobrachium vollenhovenii, büyüme ve ölüm parametreleri, stoka katılım modeli, avlanma olasılığı, stoka katılan birey başına ürün, mevcut sömürme oranı üzerinde çalışmalar yapılmıştır. von Bertalanffy büyüme parametrelerinde elde edilen tahminler şu sonuçları vermiştir: L∞ = 14.2 cm, k = 1.0 $yıl^ {-1}$ , ve $t _0$ = -0,195 $yıl^ {-1}$ büyüme performans endeksiyle, Ф' of 2,303. “Boy kompozisyonu üzerinden tahmin” yöntemiyle toplam ölüm, “z” 5,36 $yıl^ {-1}$ olarak hesaplanmıştır. Pauly’nin ampirik formülüyle hesaplanmış doğal ölüm m, 2,20 $yıl^ {-1}$ olarak, z - m le hesaplanan avcılık ölümü F 3,16 $yıl^ {-1}$ olarak hesaplanmıştır. Ölüm tahminlerine dayanarak mevcut sömürme oranı E, F/Z le hesaplanarak 0,59 bulunmuştur. Bu sonuç, göletteki bu türün aşırı sömürülmenin eşiğinde olduğunu işaret etmektedir. Tahmini büyüme katsayısı değeri kullanılarak, “k”, yaşam süresi yaklaşık 3 yıl olarak bulunmuştur. Avlanma rutini olasılığından elde edilen tahminler, ilk avlanmada boyunu, $L _c$ 3,07 cm olarak verirken avların dağılım büyüklükleri ise stoka katılım açısından bir yılda iki eğilim olduğunu öne sürmektedir. Bu yüzden balıkçılık işletmesi için mülkiyet hakkı esasına dayanan sistemin uygulanması gerektiği, bu şekilde balıkçıların Macrobrachium balıkçılığının yönetiminde işbirliği yapabileceği önerilmektedir.

Anahtar Kelimeler:

populasyon dinamiği, Macrobrachium, büyüme faktörleri, ölüm oranı, iri karides

Dawhenya göletinde Afrika Nehir Karidesinin, Macrobrachium vollenhovenii, populasyon dinamikleri

Studies were conducted on the growth and mortality parameters, recruitment pattern, probability of capture, yield-per recruit, and present rate of exploitation of the African river prawn, Macrobrachium vollenhovenii from Dawhenya impoundment, Ghana. Estimation of the von Bertalanffy growth parameters gave; L∞ = 14.2 cm, K = 1.0 $yr^ {-1}$ , and $t _0$ = -0.195 $yr^ {-1}$ with the growth performance index, Ф' of 2.303. From the linearised length-converted catch curve, total mortality, Z was 5.36 $yr^ {-1}$ . Natural mortality, M calculated from Pauly’s empirical formula was 2.20 $yr^ {-1}$ and fishing mortality, F calculated from Z - M was 3.16 $yr^ {-1}$ . From the mortality estimations, the present rate of exploitation, E calculated from F/Z was 0.59 indicating that, the species is on the verge of being over-exploited in the impoundment. Using the estimated value of the growth coefficient, K, the longevity was found to be about 3 yrs. Estimations from the probability of capture routines gave the length-at-first capture, $L _c$ as 3.07 cm while the size distribution of the catches suggest two recruitment pulses in a year. It is therefore recommended that, the property right-based system for fisheries management should be implemented so that fishermen can cooperate in the management of the Macrobrachium fishery.

Keywords:

population dynamics, Macrobrachium, growth factors, mortality, prawns,

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