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The reproductive cycle of Octopus cyanea in southwest Madagascar and implications for fisheries management

Abstract

The Octopus cyanea fishery is the most economically important fishery in southwest Madagascar. Growing concerns over the sustainability of exploitation have promoted a number of conservation efforts to improve management of the fishery. We analyse one year of catch data to identify seasonal variations in sexual maturity and key reproductive periods of the species, using microscopic analysis of gonad tissues to validate field assessments of maturity. Data show seasonal variability in maturity and size at first maturity for both sexes, as well as temporal changes in the sex ratio of the species. Maturity occurred at a minimum mean weight of 2246 g for females and 643 g for males. A clear relationship between gonad weight and total weight in male octopus indicates that total weight can be used as a proxy for sexual maturity in males. Conversely, females show high variability in weight at first maturity and no clear relationship between total weight and maturity stage. Fully sexually mature females were very rare, constituting less than 1% of the total sample. We hypothesise that the artisanal fishery may not be currently exploiting mature female individuals because females retreat to deeper waters prior to reproduction, thus remaining beyond the reach of the fishery. An abundance of juvenile individuals in the catch from June, and again from October to November, indicates recruitment peaks at these two times. In recent years, management of this species in southwest Madagascar has focused on short-term closures to fishing within specific tidal reef flat areas. Identification of the key phases of the reproductive cycle of O. cyanea in southwest Madagascar may provide managers with biological evidence to support seasonal closures designed to protect key life stages of the species.

Keywords:

Octopus cyanea

Fisheries management

Reproductive cycle

Recruitment

Depth-refuge

Southwest Madagascar

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2012
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Raberinary, D. & Benbow, S. (2012) The reproductive cycle of Octopus cyanea in southwest Madagascar and implications for fisheries management. Fisheries Research. 125– 126. 190– 197.
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Cabo Verde

At least 6,000 fishers and 3,500 processors – mostly women – and sellers are active in the fisheries sector. Almost all artisanal-caught fish is sold and consumed locally, but fish from the distant-water industrial fleet accounts for 80% of exports from Cabo Verde.

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Unlike other countries in West Africa, there is no practice of community management in Cabo Verde, although there are a variety of community associations on the islands that represent fishers’ interests. BV is supporting partner organisations to strengthen the capacity of these groups to move towards the co-management of marine resources and the development of community-driven protected areas.

The Gambia

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In the southernmost Trang province we are supporting communities reliant on nearshore fisheries − in particular for crab, shrimp and squid − in partnership with the Save Andaman Network (SAN). The region is renowned for its vibrant seagrass meadows and vast mangrove forests, which provide essential ecosystem services to coastal communities.  We’re providing training and tools to aid community- led fisheries monitoring and ecosystem management, and building community-owned social enterprises that fund and sustain local conservation efforts.

Timor-Leste

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We’re helping communities reinvigorate traditional community governance practices − known as Tara Bandu − to support marine conservation, in particular through the use of temporary and permanent fishing closures, and community-led monitoring of marine ecosystems and fisheries.

We’re helping communities come together to exchange their experiences of conservation across their shared coastline, building a new movement of local support for systems change in the management and conservation of Timor-Leste’s coastal waters.

Alongside our community conservation efforts, we have also pioneered Timor-Leste’s first homestay association, which has provided income from visiting ecotourists on Atauro Island.

Our team in Timor-Leste’s capital Dili works closely with government, civil society organisations and NGO partners.

Tanzania

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The Government supports the use of co-management to improve the management of marine resources, but a community’s ability to be meaningfully involved in this partnership approach is all too often hampered by the capacity of its institutions, to organise and to acquire the skills and resources they need. 

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Our CSO partners include Kilwa BMU Network, NYAMANJISOPOJA CFMA and Songosongo BMU, while our government partners comprise the Ministry of Fisheries in Mainland Tanzania, and the Ministry of Fisheries in Zanzibar, as well as local government authorities in Pangani and Kilwa.

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We have supported community-led marine conservation in Indonesia since 2016. Our team works in close partnership with 17 Indonesian organisations supporting community-based approaches to coral reef and mangrove conservation across 81 communities in fourteen provinces, collectively reaching over 80,000 people. 

Since 2019 we have brought these partners together within a peer learning network of Indonesian organisations specialised in supporting community-based marine conservation. The network is based on the shared values of the organisations, including a commitment to promote the rights of traditional fishing communities in conservation. Our support across these communities is customised to each context − the local fisheries, community stakeholders, seafood supply chains, legal frameworks and customary traditions governing fisheries management and conservation.

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We are working closely with our local partners Forkani, Yayasan LINI, Yapeka, Yayasan Planet Indonesia, Foneb, Komanangi, JARI, Ecosystem Impact, Yayasan Tananua Flores, Yayasan Baileo Maluku, AKAR, Japesda, Yayasan Citra Mandiri Mentawai, Yayasan Mitra Insani and Yayasan Hutan Biru, Yayasan Pesisir Lestari and Lembaga Partisipasi Pembangunan Masyarakat (LPPM) Ambon.

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Overfishing has led to a reduction in fish catches, challenging the future of many traditional fishing communities.

Our partnership is working to build the capacity of communities to manage coastal fisheries,  and improve the health of fishing communities, for the long-term wellbeing of both the communities and their fishing grounds.

Kenya

Kenya’s coast supports an extraordinary diversity of tropical marine and coastal habitats.  These waters are threatened by a proliferation of destructive fishing practices and over-harvesting within the artisanal and commercial fishing sectors.

Our approach in Kenya focuses on strengthening Beach Management Units (BMUs) to improve fisheries management. Since 2016 our Mombasa-based technical team has provided support, mentoring and assistance to local partners including Coastal and Marine Resource Development (COMRED), the Lamu Marine Conservation Trust (LAMCOT), Bahari Hai, and Kwale Beach Management Unit Network (KCBN), a network of 23 BMUs in Kwale County

These partnerships have seen notable achievements in community-led fisheries management and conservation, including training and mentoring BMU leaders in eighteen communities in Kwale and Lamu Counties.

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The Comoros islands are located in the northern Mozambique Channel, a region home to the world’s second highest marine biodiversity after the Coral Triangle. This globally important biodiversity underpins coastal livelihoods and food security, but is at risk from climate change and overexploitation of inshore fisheries.

We have maintained a presence supporting locally led marine conservation and fisheries management in Comoros since 2015, providing support to local partners, governmental institutions and communities.

On Anjouan, the second largest and most densely populated island in the Comoros archipelago, we work closely with national NGO Dahari. Our partnership has developed a replicable blueprint for community-based marine management, which has included a number of temporary and permanent marine closures − designed to safeguard the coral reef ecosystems underpinning the archipelago’s coastal economy.

This approach, which is expanding rapidly across the Comoros, is also demonstrating the importance of inclusive conservation in empowering women − through local women’s fisheries associations − to play a leading role in fisheries monitoring and decision making.

Belize

Belize’s marine environment encompasses some of the most diverse marine ecosystems in the Caribbean Sea, including vast coral reefs, mangrove forests and seagrass beds. We have maintained a permanent presence in Belize since 2010, supporting diverse fisheries and conservation efforts.

We work in close partnership with the Belize Fisheries Department, MPA managers, fishing cooperatives and fishers’ associations, and championed the establishment of a national scale domestic fishery targeting the invasive lionfish.  We are actively promoting community led fisheries management, building on the success of our pioneering work with management of invasive lionfish.

We’ve led a decade-long MPA monitoring and evaluation programme in Bacalar Chico Marine Reserve, and provide regular training in coral reef monitoring methods to MPA authorities across Belize, including helping establish management targets for Turneffe Atoll Marine Reserve, Belize’s largest MPA.

Our team supports and strengthens  fishing associations that advocate for the rights of their communities to be involved in decision making around access and use of coastal fisheries and to be key members of MPA management groups. Across the country we are working to ensure that fishers interests are mainstreamed in the design and implementation of marine conservation and fisheries management, improving the effectiveness of co-management of coral reef, mangrove and seagrass areas.

Mozambique

Extending for some 2,700km, Mozambique’s coastline is the third longest in the Indian ocean and supports millions of people with food and income. 

Our Mozambican team has worked with communities to develop locally led approaches to fisheries management and marine conservation since 2015. Our approach is focused on supporting and strengthening local organisations and Community Fisheries Councils (CCPs) to better understand their local fisheries, make informed management decisions to rebuild fisheries, and assess the impact of management actions. This work is developed in close collaboration with our partners Oikos- Cooperação e Desenvolvimento in Nampula province and Love the Ocean in Inhambane province.

Ongoing security challenges have afflicted coastal communities and emerging marine conservation efforts in several areas of Cabo Delgado, where our work is regrettably now on hold.

Madagascar

Blue Ventures’ journey began in Madagascar in 2003, and we’ve been supporting communities in marine conservation across the country ever since. We have five regional field programmes along Madagascar’s west coast, as well as regional offices in the towns of Ambanja, Mahajanga, Morondava and Toliara. Our national headquarters is located in the capital Antananarivo.

Across all these sites we support communities with the establishment of locally managed marine areas (LMMAs), and work with government partners to secure national recognition for community conservation initiatives. First developed in Madagascar by Blue Ventures in 2006, the LMMA concept has since been replicated by communities at hundreds of sites over thousands of kilometres of coastline, now covering almost one fifth of Madagascar’s inshore seabed. Our research in Madagascar has demonstrated globally important evidence of the benefits of LMMAs to fisheries and conservation.

Our work focuses on strengthening community institutions in marine management and governance, and pioneering new approaches to catalyse community engagement in ocean conservation. These innovations have included establishing community led ecological monitoring and the country’s first mangrove blue carbon project.

At the national level, we partner with the LMMA network MIHARI, which brings together 25 partner conservation organisations supporting 219 LMMA sites across the country. Our policy team is also actively involved in advocating for more robust legislation to safeguard the rights and interests of fishing communities, and to remove destructive industrial fishing from coastal waters. In 2022 we supported the launch of Fitsinjo, an industrial fisheries watchdog organisation. The network highlights industrial fishing and IUU activities in Madagascar and the broader Western Indian Ocean region.

Given the lack of basic services in remote coastal regions in Madagascar, we also help communities access basic healthcare through training and supporting women to serve as community health workers. We do not replace government health systems, but work to strengthen existing structures in close collaboration with government health actors and specialist NGOs. We also incubate Madagascar’s national health-environment network, which brings together 40 partner organisations to address the health needs of communities living in areas of conservation importance across the country.