Message from oceans past: Good management helps ocean life to recover
Human life on the Planet Earth depends on its oceans. Since 1990, the output of fisheries has stagnated below 100 million tonnes per year in spite of the massive investment in high-tech vessels and gear, and the opening up of distant and deep waters in the Southern Hemisphere. The Earth’s oceans simply will not yield more. Marine habitats are under severe pressure from exploitation, the torment of offshore structures, and nutrient run-offs from land use. But what is the scale of change? What used to be in the sea before humans began impacting on marine ecosystems and habitats?
How historical research can inform us of the scale of human impact through time will be a focus of discussion at a major conference 18-20 November in Dublin, Ireland. Oceans Past III is the third in a series of organized conferences as part of the Census of Marine Life’s History of Marine Animal Populations (HMAP) project. HMAP provides baselines of marine life abundance and species distribution during past periods, against which present stocks can be compared. Researchers in natural sciences and humanities from around the world, 48 in all, are expected to participate in the conference and just a touch of the results that will be presented are described here:
Poul Holm, the chair of HMAP, explains: “Historical research informs us of how much mankind depended on ocean resources for economic, social, and cultural needs. And we need this knowledge to manage life in the oceans wisely. Fortunately, only a few species have gone extinct. The oceans are wide and deep, and many species may rebuild their own stocks if we let them. Knowing what used to live in the sea, therefore, informs us about what might again live there if we allow the populations to grow.”
Turtles and Sharks, Oaxaca, Mexico
The global demand for turtle leather in the second half of the twentieth century led to a rapid depletion of Olive Ridley sea turtle stocks in the southern Mexican state of Oaxaca. The Mexican federal government banned all sea turtle captures in 1990. This, coupled with previous conservation measures during the fishery years, led to a speedy recovery of sea turtle populations. As part of the fishery conservation efforts, eggs from slaughtered females were incubated, and the resulting hatchlings were released into the sea. The Olive Ridley takes 12-15 years to reach reproductive age, so the recovery time coincides with the maturation time of the hatchlings released a generation earlier. Today, the population of Olive Ridley turtles on the coast of Oaxaca has recovered and continues to grow. Yet, due to an increase in demand for shark fins in East Asian markets, shark fishing quickly replaced turtle captures as an important source of income. And history soon repeated itself, as the shark populations rapidly declined. Michelle María Early Capistrán who conducted the research says, “The turtles are out of danger, but their safety was achieved at the expense of the sharks.” The fishing efforts for both sharks and turtles in the region grew as a result of growing demands from a global market. This is a clear example of how changes in global and local economic priorities can have a direct impact on marine animal populations, and how marine animal conservation is, at its very root, a political and economic problem.
Shark Fins and Turtle Leather: Historic Marine Animal Exploitation on Mexico’s Southern Pacific Coast. By: Michelle María Early Capistrán.
Sharks, Northern Adriatic Sea
In Chioggia’s fish market, in the Northern Adriatic Sea, elasmobranch landing greatly declined in the last 50 years. Elasmobranchs are sharks, skates and rays, whose bodies have a cartilage structure instead of a skeleton, and are among the most vulnerable species of the oceans. Their populations are on a worldwide decline. Thirteen species are currently landed, but one shark, the common smooth-hound: Mustelus mustelus, represents more than 60% of the total elasmobranch landing. Researchers develop models by using historical and present data to predict population trends under different management scenarios. These models predict that without proper management, the common smooth-hound population will decrease by approximately 80% in the next 50 years. Considering the elasmobranch’s high survival rates when released at sea after being caught, the models demonstrate that protection of juveniles proved to work far better than just reducing the fishing effort. The combination of historical and present data and modeling makes this management scenario realistic and feasible.
Which future for elasmobranch in the Northern Adriatic Sea? An answer integrating historical data and predictive models. By: Yuri Artioli, Eleonora Visentin, Alberto Barausse, Carlotta Mazzoldi.
Coral Reef, Hawaii
Coral reef ecosystems are among the most diverse coastal ecosystems in the world. Researchers have reconstructed coral reef ecosystem conditions over the past 700 years, in the Hawaiian archipelago by integrating archaeological data, anecdotal and ethnographic information, and modern ecological, and fisheries data on marine species. The researchers discovered that humans, in at least two cases, played a positive role in the recovery of coral reefs. Prior to western contact, Native Hawaiian societies developed large-scale aquaculture systems and implemented effective management practices that sustained communities and coral reef ecosystems in the main Hawaiian Islands. After western contact the remote northwestern Hawaiian Islands have benefited from over a century of conservation and ecosystem protections, including the recent designation of this region as the fully protected Papahānaumokuākea marine national monument. The results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to a long-term path of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity to be resilient to human impacts. Understanding environmental challenges of the past provides promise for contemporary efforts to manage ecosystems and societies toward social-ecological sustainability.
Oceans Past III Conference, 2010
International scientists from two dozen countries will travel to Dublin for the third Oceans Past conference (www.hmapcoml.org/oceanspast) hosted by Trinity College, 18-20 November, where they will share additional surprises such as these:
- Dutch 17th and 18th century fishing skippers were among the smartest groups of people in all of early Modern Europe. During the later half of the 18th century, skippers from Schiedam were at the top of a list based on average skills in logic and reasoning for close to 40 groups of people from various branches of society in Western Europe. The skills needed to fish have been highly appreciated for centuries, and the Dutch herring fishermen, who out-performed other countries’ fishermen, certainly profited from their keen abilities to navigate, count and keep books. Out at sea, they were supermen gathering the silver darlings of the North Sea.
- The world of fantasy and myth has dominated all zoological representations from the medieval era to the centuries of the great explorations. Inspired by the past, nature and species are now described and reinvented in all their totemic power by the art project Fishars.
- In some coastal communities in the Philippines fishing practices were guided by beliefs of sea spirits, often accompanied by elaborate ceremonies. As societies are transformed by socio-economic and cultural factors, beliefs are being lost and perceptions changing that ultimately will have bearing on how well efforts to conserve or manage marine animal populations will succeed.
Oceans Past III Conference Scope
The first decade of international, multi-disciplinary “History of Marine Animal Populations” (HMAP) research program culminates in 2010. At this juncture, it is appropriate to reflect on the project’s major achievements, to look ahead and consider the future of marine environmental history and historical ecology, and to consider how the knowledge assembled to date can be applied to marine resource management and conservation.
Dublin conference themes include:
- New evidence of historical change in marine animal populations and ecosystems
- Data management, modeling, and visualization in marine historical ecology
- Linking history and science to policy and management.
- Stories from the Sea: narratives, perceptions and representations of marine animals
- Interaction between Human and Marine Animal Communities – long term changes in social and economic priorities.