Skip to main content

DNA analysis to confirm octopus species present in catch from Southwest Madagascar fishery.

  • Over 100 octopus samples to be collected and analysed.
  • Supporting improvements in octopus fishery management across Southwest Indian Ocean region.

Start date: April 2023


Student Research Grant


Cretus Joseph Mtonga, Leibniz Centre for Tropical Marine Research, Germany


Southwestern Madagascar octopus fishery

Clarifying composition of octopus catch

Until recently, catch from the Southwestern Madagascar octopus fishery was thought to consist of a single species, the Day octopus (Octopus cyanea). However, research has suggested at least one other species may be present.

A new study, supported by the MSC’s Ocean Stewardship Fund, will identify whether multiple species of octopus occur. This will allow for more accurate stock assessments to be carried out and contribute to the development of management measures to prevent overfishing.

The long-term health of the stock is vital to the coastal communities that depend on the octopus fishery for an income and a source of food. Octopus fishing is a particularly crucial livelihood for women, who have limited means of earning money.

Genetic ‘barcodes’ to determine diversity

Cretus Joseph Mtonga, a PhD Student at the Leibniz Centre for Tropical Marine Research, will carry out genetic tests on over 100 samples of octopus from the Southwest Madagascar fishery.

DNA from each tissue sample will be analysed through a technique known as ‘genetic barcoding’ to establish whether different species of octopus are present. The genetic sequences will be compared against a database of octopus DNA gathered from fisheries in East Madagascar, Kenya, Tanzania and Mozambique to identify exactly which species have been caught.

As well as advancing understanding of species diversity within the fishery, better identification of different octopus species will help ensure products are accurately labelled when sold.

Young man in white labcoat and blue surgical gloves standing at counter with DNA extraction machinery

© Debora Benjamen

“This fund provides an opportunity for early career researchers like me to [carry out] applied research that has a direct impact on ocean sustainability.”

Cretus Joseph Mtonga

Leibniz Centre for Tropical Marine Research

Improving octopus management at scale

The Southwest Madagascar Fishery is currently part of a Fisheries Improvement Project, and the findings from the research will support efforts to meet the requirements of the MSC Fisheries Standard.

The study will also contribute to wider ambitions across the entire Southwest Indian Ocean region to better understand the genetic structure of octopus stocks and drive improvements in sustainable fisheries management.