The effects of climate change on aquaculture in the Western Cape of South Africa

Thesis (MScConsEcol)--Stellenbosch University, 2024.

ENGLISH ABSTRACT: This thesis investigates the impacts of climate change on the aquaculture sector in the Western Cape, South Africa, focusing on both marine and freshwater systems. With global wild fish stocks under significant pressure due to overfishing and climate change, aquaculture has emerged as a critical sector for ensuring food security. However, aquaculture itself is not immune to climate-related challenges, including in regions like the Western Cape, where rising temperatures, erratic rainfall, and shifts in marine conditions are becoming more frequent. The study's primary objectives are to evaluate the effects of climate change on aquaculture production, explore the perceptions of climate change among aquaculture farmers, and assess their adaptive capacity. The thesis is divided into three key chapters: an introduction to the Western Cape's aquaculture sector and climate challenges, a literature review of climate trends and their effects on aquaculture, and a detailed results-discussion based on primary data collected from aquaculture farms. Chapter 1 provides a comprehensive overview of aquaculture in the Western Cape, tracing its origins from early attempts at cultivating oysters in the 17th century to the present-day operations. It outlines the historical context, the current state of the sector, and highlights some of the pressing environmental challenges that threaten its sustainability. Various production systems and value chains associated with each cultured species are discussed, emphasizing the sector's economic importance. Chapter 2 reviews existing literature on climate change's effects on aquaculture, particularly in the context of the Western Cape. Key climate change risks include rising temperatures, shifting rainfall patterns, and the growing occurrence of harmful algal blooms. These changes have adverse impacts on fish growth, mortality rates, feed requirements, and the sustainability of aquaculture operations. The review also examines potential adaptation strategies, including selective breeding for thermal tolerance, changes in feed management, and infrastructure modifications to mitigate environmental stressors, among others. Chapter 3 presents the findings of a survey conducted among 32 aquaculture sector participants across the Western Cape. The survey captures farmers' perceptions of climate change, its impacts on their operations, and the strategies they are adopting to cope with climate variability. Marine farmers, particularly those involved in mussel, oyster, and abalone farming, report significant impacts from ocean warming, increased acidity, and harmful algal blooms. Freshwater farmers, including those cultivating trout and tilapia, face challenges related to droughts, water scarcity, and rising temperatures. While many farmers have taken adaptive measures-such as water conservation, changing feed practices, and diversifying production, among others- some of these strategies may be standard operating procedures rather than direct responses to climate change. Additionally, there remain considerable barriers to further adaptation, including financial constraints and socio-economic issues like load shedding which may overshadow the gradual effects of climate change. This thesis concludes that the aquaculture sector in the Western Cape is vulnerable to climate change yet holds significant potential for adaptation and growth. With targeted support, innovative technologies, and a focus on building resilience, the sector can continue to contribute to food security and economic development in the province. The study emphasizes the importance of strong coordination among all stakeholders and fostering collaboration between government, sector participants, and academia to ensure the sector's sustainability. By addressing these challenges, the Western Cape can position itself as a leader in climate-resilient aquaculture, contributing to both local food security and global sustainability efforts.

AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die impak van klimaatsverandering op die akwakultuursektor in die Wes-Kaap provinsie van Suid-Afrika. Dit fokus op beide mariene en varswaterstelsels. Met wilde visbronne wat wereldwye onder druk verkeer weens oorbevissing en klimaatsverandering, het akwakultuur na vore getree as 'n kritieke sektor om voedselveiligheid te verseker. Akwakultuur is egter nie immuun teen klimaatsverwante uitdagings nie, insluitend in die Wes-Kaap, waar stygende temperature, onvoorspelbare reenval, en veranderinge in mariene toestande toenemend voorkom. Die studie se primere doelwitte is om die effekte van klimaatsverandering op akwakultuurproduksie te evalueer, die persepsies van klimaatsverandering onder akwakultuurboere te verken, en hul aanpassingsvermoe te assesseer. Die tesis is verdeel in drie hoofhoofstukke: 'n inleiding tot die Wes-Kaap se akwakultuursektor en klimaatsuitdagings, 'n literatuuroorsig oor klimaatsneigings en hul effekte op akwakultuur, en 'n gedetailleerde resultate-en-bespreking gebaseer op primere data wat van akwakultuurplase versamel is. Hoofstuk 1 bied 'n omvattende oorsig van akwakultuur in die Wes-Kaap, vanaf die vroee pogings om oesters in die 17de eeu te kweek tot die hedendaagse bedrywighede. Dit beskryf die historiese konteks, die huidige stand van die sektor, en stel sommige van die dringende omgewingsuitdagings wat die volhoubaarheid daarvan bedreig, bekend. Verskeie produksiestelsels en waardekettings geassosieer met die verskillende kommoditeite word uitgelig, met klem op die ekonomiese belang van die sektor. Hoofstuk 2 hersien bestaande literatuur oor die effekte van klimaatsverandering op akwakultuur, spesifiek in die konteks van die Wes-Kaap. Sleutelrisiko's van klimaatsverandering sluit in stygende temperature, veranderende reenvalpatrone en skadelike algbloeis wat toenemende meer voorkom. Hierdie veranderinge kan nadelige wees vir organismes se groei, mortaliteitskoerse verhoog, voervereistes verander, en die volhoubaarheid van akwakultuuroperasies be"invloed. Die oorsig onder andere ondersoek ook moontlike aanpassingsstrategiee, insluitend selektiewe telling vir temperatuur verdraagsaamheid, veranderinge in voedsel bestuur, en infrastruktuurwysigings om omgewingstresfaktore te versag. Hoofstuk 3 bied die bevindinge aan van 'n opname, wat onder 32 rolspelers binne die Wes-Kaapse akwakultuurbedryf uitgevoer is. Die opname dokumenteer boere se persepsies van klimaatsverandering, die impakte daarvan op hul bedrywighede, en die strategiee wat hulle aanneem om klimaatsvariasies te hanteer. Mariene boere, veral die wat betrokke is by mossel-, oester-, en perlemoenboerdery, rapporteer impakte van oseaanverwarming, versuring, en skadelike algbloeisels. Varswaterboere, insluitend die wat forel en tilapia kweek, ervaar uitdagings wat verband hou met droogtes, waterteskorte, en stygende temperature. Alhoewel baie boere aanpassingsmaatreels getref het-soos waterbewaring, veranderinge in voerpraktyke, en diversifikasie van produksie, kan sommige van hierdie strategiee as standaardbedryfsprosedures beskyf word - eerder as direkte reaksies op klimaatsverandering. Daar is ook aansienlike hindernisse vir verdere aanpassing, insluitend finansiele beperkings en sosio-ekonomiese kwessies soos kragonderbrekings wat die geleidelike effekte van klimaatsverandering kan oorskadu. Ten slotte die akwakultuursektor in die Wes-Kaap is kwesbaar is vir klimaatsverandering, maar beskik aansienlike potensiaal vir aanpassing en groei. Met die regte ondersteuning, innoverende tegnologiee, en 'n fokus op veerkragtigheid, kan die sektor voortgaan om byte dra tot voedselveiligheid en ekonomiese ontwikkeling in die provinsie. Die studie beklemtoon die belangrikheid van sterk koordinasie onder rolspelers en die bevordering van samewerking tussen die akwakutuursektor rolspellers, regering, en akademia om volhoubaarheid te verseker. Deur hierdie uitdagings aan te spreek, kan die Wes-Kaap posisioneer word as 'n leier in klimaats-volhoubare akwakultuur, wat bydra tot beide plaaslike voedselveiligheid en wereldwye volhoubaarheidspogings.

Masters