The fisheries value of mangroves in Honduras

kayaking in mangroves, Honduras

Surveying mangroves in Honduras

Mangroves may increase the abundance of coral-reef fish, according to a new study at Utila, Honduras. Fished species such as snappers, grunts, and barracudas use mangroves as juveniles before migrating to coral reefs as adults.

Mangroves are the predominant vegetative habitat found at the interface between sea and land of tropical and subtropical zones. Since 1980, 20% of the world’s mangroves have been destroyed for land reclamation, shrimp aquaculture, and wood for fire and building materials (World Mangrove Atlas).

Red mangrove roots provide fish with spatially complex habitat that attracts food and creates refuge from predators

Two-thirds of the island of Utila (Bay Islands, Honduras, Central America) is covered by mangroves, but, as elsewhere in the world, these mangroves are currently being removed.

The role of mangroves

transects surveyed

Mangroves are thought to act as nurseries for many species of tropical fish

Previous scientific studies have found that these trees are essential to reef health and coastal protection. In addition, mangroves are thought to act as nurseries for many species of tropical fish.

Nursery reef fish species require habitats other than coral reefs while in the juvenile stage.

Red mangroves grow at the water’s edge and their roots, which are used for support and oxygen transport, provide these fish with a complex spatial habitat that both attracts food and creates a refuge from predators.

Surveying fish abundance

Sampling and surveying were conducted on the surrounding reefs and mangroves of Utila, Bay Islands and the Cayos Cochinos Islands, Honduras in 2007 and 2008. Utila, which has 13 cays, is the southernmost island in the Bay Island archipelago and is located 29 km off the coast of Honduras. Utila is dominated by mangroves (nearly 66% coverage). The mangroves, Rhizophora mangle and Avicennia germinans, dominate two large lagoons on the south side and mangrove stands on the north side of the island.

Fisheries management with mangroves

Figure 1 - the abundance of fish at the two islands

Cayos Cochinos consists of Cayos Menor, Cayos Mejor and 13 smaller coral cays. The islands are located southeast of the Bay Islands, 18.5 km from the mainland. In contrast to Utila, Cayos Cochinos has a distinct absence of mangrove lagoons and supports only two very small mangrove stands with lengths of 100 and 150 metres.

Coral reef surveys consisted of eight randomly selected 50m transects at each site (six sites per island) where fish abundances were recorded. To establish which coral-reef species use mangroves as a juvenile nursery (aka nursery species), nine mangrove sites were surveyed using 30m transects.

Of the 13 nursery species whose juveniles were found primarily in mangroves, eight had significantly higher abundances (denoted by asterisk on Figure 1) on mangrove-rich Utila’s coral reefs. The remaining five species were also more abundant on Utila, but were not significantly so.

Some non-nursery adult fish species had higher abundances on Utila as well, but a larger percentage of nursery species than non-nursery species had higher abundances on Utila (see Figure 2).

Figure 2 pie chart nursery fish abundance

Figure 2 - pie charts show the abundance of nursery and non-nursery fish

Overall, coral-reef fish communities of the two islands were significantly different from each other. Therefore, this comparison between coral reefs off a mangrove-rich island and a mangrove-poor one indicates that mangroves may increase the abundance of nursery coral-reef fish, and adds one data point (island comparisons of fish nursery species) to a large scale graph of comparable matched-pairs from previous studies.

Conflicts of tourism

In 1993, Honduras recognised the importance of mangroves by signing the Ramsar Convention, an international treaty promoting the conservation of wetlands. Yet, many mangroves have been destroyed or are threatened with destruction on Utila as development stimulated by eco-tourism encroaches. The irony here is excruciating. Tourists are drawn to the Bay Islands to explore coral reefs, and yet, in decimating mangroves, tourism directly threatens the health of those reefs.

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5 Responses to “The fisheries value of mangroves in Honduras”

  1. Hi. Great work.
    Is this study being published?
    Perhaps you’d like to do some MangroveWatching?
    MW

    • Jessica Jaxion-Harm Reply August 2011 at 11:03 am

      Dear Mangrove Watch,

      Yes, this study has been published:

      Harm J (2008) Differences in coral-reef fish assemblages on mangrove-rich and mangrove- poor islands. Proceedings of the 11th International Coral Reef Symposium, Fort Lauderdale, FL, USA: 296-300.

      I also have another paper in press:

      Jaxion-Harm J, Saunders J, Speight M (accepted Aug. 13th, 2011) Distribution of fish in seagrass, mangroves, and coral reefs: life-stage dependent biotope utilization in Honduras. Revista Biologia Tropical

      …and two more manuscripts in review. Let’s continue our discussion over email. My email is jessica.jaxion.harmatgmail.com

      Best Regards,
      Jessica

  2. Hi Jessica, congratulations for your study! We would like to publish the abstract in dosmares.org web site, including links of how to obtain the original paper. If you are interested please visit our web site and go to “abstracts” to see how this work, then you can send the information by email. This service is free. Best regards.

  3. Dr. Prabhakar R. Pawar Reply November 2013 at 11:47 am

    Dr. Prabhakar R. Pawar
    Vice-Principal & Head, Department of Zoology,
    Veer Wajekar A. S. C. College. Phunde (Uran),
    Navi Mumbai – 400 702, INDIA
    prpawar1962@rediffmail.com
    4th Nov 2013
    Dear Sir,
    I am working on the population density, biomass and diversity indices of macrobenthos from mangroves of Navi Mumbai.
    For reference, kindly send me your research papers related to above work.

    With Warm Personal Regards,

    Thanking you,

    Dr. Prabhakar R. Pawar

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