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The Once and Future Common

The conservation of biodiversity through the use of information contained in The IUCN Red List is especially tailored towards the conservation of species that are threatened with extinction. It is natural that the affinity and resources for conservation would turn towards these species and in this regard The IUCN Red List has been exceptionally valuable in guiding conservation work that helps prevent extinction. But, if the goal is holistic biodiversity conservation (it is!) then it is essential that conservation seeks to conserve species as part of larger assemblages, like ecosystems. In this regard, common native species are often in a prime position to provide critical information on the health of broad species assemblages and ecosystems.

Common Tortoise (Testudo graeca) VU_copyright Tommi Sandberg
The Common Tortoise (Testudo graeca) is native to the general Mediterranean region where it clearly composes several subspecies. The abundance of this species varies greatly across its range where it is still locally common in some areas but extremely depleted in others. For instance, populations in some areas of Morocco were estimated to have suffered over 90% decline over the period 1900-1984. This species is commonly kept as a pet and is also under intense pressure from urban development of its habitat, threats that are not likely to decline in the future without concerted conservation effort. Photo Courtesy of Tommi Sandberg

Perhaps one of the most challenging aspects of modern species conservation is the shifting perspective of what constitutes a healthy ecosystem. Generally, what you would consider a healthy ecosystem is based on your experiences with nature as children, although the wealth of historical accounts on the extent of species show a very different picture of life on Earth. For instance, when Europeans first began fishing the Grand Banks off the Canadian East Coast, there were so many fish that they literally fished with weighted buckets, hauling up round after round of enormous, 200 pound codfish. Each generation has a different perspective on what a healthy ecosystem looks like and there is evidence that the erosion of global biodiversity combined with the typical human lifespan have produced a situation where conservation is aimed at conserving biodiversity to acceptable levels that are far less than their historical maximums.

Atlantic Cod (Gadus morhua) VU_copyright Joachim S. Müller
The Atlantic Cod (Gadus morhua) was once one of the most common fish in the North Atlantic. During the early 1990s the global population of this species crashed as it had been fished to less that 95% of its historical population size. This fishery collapse not only had enormous consequences for human livelihoods, but fundamentally altered the food chain and the way other species interact with one another in the North Atlantic Ocean. Before its general extirpation, cod were a top tier predator and a cessation of the cod fishery has not yet led to the recovery of this species. Photo Courtesy of Joachim S. Müller

Although we have made tremendous advances in conservation science and policy in the past 50 years, the baselines of global biodiversity have shifted faster than the pace of species discovery or measurement, especially in the oceans. It wasn’t until the Decade of Biodiversity from 2000–2010 that science began to accumulate a truly global picture of biodiversity through coordinated national analyses of biodiversity—much of which has been based upon or influenced by IUCN Red List assessments.

Common Hippopotamus (Hippopotamus amphibius) VU_copyright Tarique Sani
In 1996, Common Hippopotamus (Hippopotamus amphibius) populations were considered widespread and secure. Since then, there have been substantial changes in several key countries where Common Hippo are found. The most recent population estimates suggest that over the past 10 years there has been a 7–20% decline in Common Hippo populations. Although the causes of the population decline are known (exploitation and habitat loss), the threats have not ceased, nor is there evidence the threats will be removed in the near future. Photo courtesy of Tarique Sani

As baselines are measured and information about species accumulates, it is becoming clearer that threatened species should not be the sole focus of our conservation attention; there are also measurable declines in many once common species. Perhaps some of the most ironic examples of the decline in common species are those threatened species that still have “common” names. For example, the Common Skate (Dipturus batis) was once one of the most abundant animals in the North Atlantic Ocean and Mediterranean Sea, but is now classified as Critically Endangered on The IUCN Red List. Similarly, the Common Hippopotamus (Hippopotamus amphibius), Common Seahorse (Hippocampus kuda), and Common Tortoise (Testudo graeca), all listed as Vulnerable, are threatened species that were once so plentiful that they were self-titled.

Common Skate (Dipturus batis)_copyright Paul Kay
The historical range of the Common Skate (Dipturus batis) covered much of the continental shelf of the North-east Atlantic, from Madeira and the coast of northern Morocco in the south, to Iceland and northern Norway in the north, including the Mediterranean Sea. This relatively large species has been most threatened by over-fishing and as by-catch during multi-species trawl fishing effort. As these fisheries are not likely to reduce their effort in the foreseeable future, a reduction in the threats to the common skate is unlikely. Photo courtesy of Paul Kay

The IUCN Red List is not only a list of threatened species, it is one of the only ways that humanity is able to scientifically account for species that are currently of Least Concern—the more common species. The IUCN Red List can be a valuable tool for conserving threatened species, but perhaps its greatest utility is that it also provides measurements on the status of common species and by extension, the broader ecosystems they form. This provides a more comprehensive outlook of species conservation that makes it possible to amplify current biodiversity towards increasing baselines and establish the momentum to conserve the once and future common species.

Common Seahorse (Hippocampus Kuda) VU_copyright prilfish
The Common Sea Horse (Hippocampus kuda) ranges throughout South East Asia, Australia, Japan, and some of the Pacific islands, including Hawaii. It is a valuable seahorse in traditional Chinese and Indian medicine, and is also a popular aquarium fish. This once common species is classified as Vulnerable due to the threats of indiscriminate catch, habitat degradation and exploitation by collectors and aquarists and its trade is regulated in the Convention on the International Trade in Endangered Species (CITES). Photo courtesy of prilfish


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By Craig R. Beatty