Captains Log

Marlin Research & Conservation

Marlin Research & Conservation

Really interesting to finally get the results from the Marlin research & conservation project that involved the collection and study of genetic tissue samples taken from billfishes distributed across the Atlantic, Pacific, and Indian oceans.

This project, with the main goal of providing critical information for improving conservation and management efforts for these species, was accomplished with the global effort of Captains and Anglers from 29 countries and five continents.

The study conducted by Dr. Nadya Mamoozadeh of the Virginia Institute of Marine Science and Dr. Sam Williams of the University of Queensland involved many other parties such as other scientists, conservation groups, and resource managers from across the globe.

I was initially contacted by Roy Bealey, then from the African billfish foundation, a few years ago, to get involved and help with the collection of billfish genetic samples from the Bazaruto Archipelago. We did so over the space of two seasons, mostly on Black Marlin, the most iconic species on the archipelago.



Marlin Research & Conservation –Black Marlin tagged and released aboard Vamizi of the Bazaruto Archipelago in Mozambique.
















The results on this species are obviously of particular interest for us and the study of Black Marlin DNA samples from across the Indo-Pacific had breakthrough results. It revealed that this species represents a single genetic population in the Indian Ocean as opposed to three distinct populations as it was previously believed.

Up to date, there are only two scientifically recognized Black Marlin Spawning grounds, both in the Pacific Ocean, where, was recognized that two genetically distinct populations occur. Although it seems these populations do mix on shared feeding grounds in the central Pacific, they then spawn in different confirmed spawning grounds. With the north Pacific population on the Great Barrier Reef and the South Pacific Population in the South China Sea.

However, what is also very interesting to us is that, finally, the scientific world is suggesting of a Black Marlin spawning off the Bazaruto Islands in the western Indian Ocean.

We are no scientist, but have through on site observation over the last two decades, believe this to be the case. There is actually very little doubt in our minds, that Bazaruto is a Black Marlin spawning area.

We have, on various occasions, seen the “mating“ behavior between young males and the very large females that are present in the area throughout September to early December.

The observation of these large fish which are sometimes extremely healthy looking and full of gonads. And at other times, thin and worn out, after spawn. More recently we have photographed gonads on a few fish that have come up dead, and scientists have agreed that some of those where ready, within a few days, of spawning.



Marlin Research & Conservation – A tail wrapped, weighted 814-pound Black Marlin caught aboard Vamizi in October 2014. Upon inspection of the Gonads photographs, scientists agreed that they seemed ready to spawn.















We hope that in the near future, this “suggested“ spawning ground can be scientifically confirmed, which would mean a breakthrough and hopefully bring some awareness to the importance of this area, not only to the scientific world but, through them to local resource and conservation groups as well as policy makers.

Our next goal is to get funding for the deployment of satellite tags into some of these big females. It would be highly interesting and extremely important from a Marlin research and conservation perspective, to know where they go and come from, outside the season. After all, nowhere else in the Indian Ocean, have Grander Black Marlin been caught, on Sportfishing boats, apart from the Bazaruto Archipelago. And, when one considers the extremely boat effort and the number of big girls caught in the area, it makes one wonder!

Where do they roam?

Anyone interested in funding and joining us in this quest can contact us at;




Marlin Research & Conservation – An estimated 900 plus Black Marlin about to be tagged and released aboard Vamizi fishing out of the Bazaruto Archipelago.















Below is the IGFA published article on this genetic research and conservation project and the findings of not only Black Marlin, but also white and striped Marlin and another possible Black Marlin spawning ground on the Indian Ocean, off the coast of Sumatra.


Marlin Research & Conservation – Mike Goch about to let go a nice size Bazaruto Black Marlin.











Duarte A. M. Rato

Sportfishing Charters @ Vilankulos & Bazaruto Archipelago


FB:                   MarlinMoz Sportfishing          &

Skype:              duarteamrato

Phone: + 258 84 639 0466



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