Understanding How Parasites from Farmed Fish May Influence Wild Fish Declines Using Epidemiological Modelling

Abstract

Beside various fields of its applications, in this study epidemiological modelling was used to understand how parasites from farmed fish may cause wild fish declines. Two separate strategic models were constructed addressing the transmission of micro-parasites and macro-parasites between farmed and wild fish: A SIR (Susceptible-Infective-Removed) model for micro-parasite infections and a compartmental density-dependent model for macro-parasite infestations. The results indicated that parasites originated in wild fish populations, after infecting farmed fish can cause epizootics. Subsequently, these parasites can be transmitted from farmed to wild fish and might have negative impact on the dynamics of wild fish populations. Sensitivity analysis of the basic model parameters in both models showed that model parameters, which are influenced by abiotic factors and allow passive manipulation, such as pathogen specific transmission rate (β), pathogen specific transmission rate between infected farmed and susceptible wild fish (δ), the rate of production of infective stages by an adult parasite (λ) and transmission rate between host and parasite infective stages (β) are more sensitive compared to model parameters which encompass chemical control and fallowing. This emphasizes the importance of the preventive medicine rather than intervention procedures in aquaculture aiming at eradicating epizootics caused by parasites and protecting wild fish stocks.

Keywords

• Aquaculture
• parasites
• epidemiology
• modelling
• wild fish

Kültür Balıklarından Kaynaklanan Parazitlerin Nasıl Yabani Balık Azalmalarını Etkileyebileceğini Epidemiyolojik Modelleme Kullanarak Anlaşılması

Öz

Çeşitli uygulama alanlarının yanı sıra, bu çalışmada epidemiyolojik modelleme kültür balıklarından kaynaklanan parazitlerinin nasıl yabani balık azalmalarına yol açabileceğinin anlaşılması için kullanılmıştır. Kültür ve yabani balıklar arasındaki mikro-parazitlerin ve makro-parazitlerin yayılımına yönelik iki ayrı stratejik model geliştirilmiştir: mikroparaziter enfeksiyonlar için SIR (Sağlam-Enfektif-Geçiren) modeli ve makro-paraziter enfestasyonlar için bölümlü ve yoğunluğa bağlı model. Sonuçlar, başta yabani balık popülasyonlarında çoğalan parazitlerin kültür balıklarını enfekte ettikten sonra belirli yetiştiricilik şartları altında epizootiklere neden olabileceklerini işaret ettiler. Akabinde, bu parazitler kültür balıklarından yabani balıklara yayılabilirler ve yabani balık popülasyonlarının dinamikleri üzerinde olumsuz etkiye sahip olabilirler. İki modeldeki temel model değişkenlerinin duyarlılık analizleri, abiyotik etmenler tarafından etkilenen ve edilgen yönetime izin veren değişkenler, örneğin mikroparaziter modelde patojene özgü yayılım hızı (β) ve enfektif kültür balıkları ile sağlam yabani balıklar arasındaki patojene özgü yayılım hızı (δ) ve makroparaziter modelde erişkin parazitlerin enfektif evre üretim hızı (λ) ile parazitin enfektif evreleri ile konakçısı arasındaki yayılım hızı (β), kimyasal kontrol ve üretim alanının boş bırakılmasını içeren model parametreleri ile kıyasla daha duyarlı olduklarını göstermiştir. Bu, parazitlerden kaynaklanan epizootiklerin yok edilmesinde ve yabani balık soyunun korunmasını amaçlayan su ürünlerindeki müdahale yöntemlerinden çok koruyucu hekimliğin önemini vurgulamaktadır.

Anahtar Kelimeler

• Su ürünleri yetiştiriciliği, parazitler, epidemiyoloji, modelleme, yabani balıklar

Kaynakça

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