Proposed listing of the Percula clownfish (Amphiprion percula) under the U.S. Endangered Species Act: What it means, and what aquarists need to know (Part 2)

by | Oct 22, 2014 | 0 comments


As discussed in Part 1 of this series, in September, 2012 the Center for Biological Diversity (CBD) petitioned the National Marine Fisheries Service (NMFS) to list the Percula clownfish (Amphiprion percula) and seven other damselfish species under the U.S. Endangered Species Act (ESA). The review for the Caribbean Yellowtail damselfish (Microspathadon chrysurus) has not yet been released. After review of the petition and internal scientific review, NMFS failed to find substantial evidence suggesting that listing was warranted for the six Indo-Pacific damselfish species. In contrast, NMFS recently released a 90-day finding regarding the Percula clownfish because the petition and NMFS’s internal scientific review yielded substantial information suggesting that listing A. percula under the ESA could be warranted. NMFS is now seeking public testimony which they will consider when determining whether or not A. percula merits listing under the ESA and if so, how the ESA should be applied to protect this species.

ESA listing of this species could have a profound impact on the marine aquarium hobby. Percula clownfish are extremely popular aquarium fish and one of the most commonly captive bred marine ornamental species today. At this point, the possible outcomes of the 90-day finding NMFS range from rejecting the proposal, which would result in no change whatsoever to the legal status of A. percula in captivity, to listing the species as endangered under the ESA, which would immediately end all commercial trade in the species in U.S. jurisdiction. If A. percula were listed as endangered, then fish which are already owned by private individuals would remain legal and would be grandfathered in at the time of listing, though some sort of permitting program would likely be required, which could be challenging to implement. Since other governing bodies consider ESA protections when extending their own legal protections, the outcome of this proposed listing has major implications for the future of the Percula clownfish in the marine aquarium hobby worldwide.

Last time we considered the details of how these species came to be petitioned for ESA listing, how the listing process works, and the implications for the marine aquarium hobby. In this article I will discuss the science related to this proposed listing. In particular, I will summarize the science the CBD cited in their petition to list these species under the ESA, the science NMFS considered in producing their 90-day finding, and will discuss additional scientific data which I believe suggests that listing the Percula clownfish under the ESA is not warranted.


ESA threat factors

In their petition, the CBD argues that four of the five threat factors listed under the ESA are endangering the continued existence of the eight petitioned fish species. In the sections below I will briefly discuss CBD’s arguments pertaining to each risk factor, NMFS’s responses to these arguments, and will present additional scientific information which I believe is pertinent to NMFS’s status review. Since NMFS is currently considering only A. percula for listing under the ESA and rejected the petition to list the other Indo-Pacific damselfish species, I will focus on the data pertaining to A. percula.


Threat factor B: Over-utilization for commercial, recreational, scientific, or educational purposes.

CBD’s argument: As mentioned last time, the CBD cited data from Rhyne et al. (2012) which shows that in 2005 more than 400,000 individuals of the A. percula/ocellaris species complex were imported into the U.S., making this the fifth most commonly imported type of marine ornamental fish. [Note: while collating import data Rhyne et al. (2012) found that the two similar-looking species A. percula and A. ocellaris often appeared to be misidentified on official import documents. Since import data for the two species could not be reliably separated, the two were lumped into a species complex in the publication (Rhyne, pers. comm).] This level of harvest, the CBD argued, is potentially unsustainable and could imperil the future of the species, especially since few data are available to assess the impacts of this level of collection on the species.

NMFS’s response: NMFS noted that no population estimates for A. percula were provided the CBD’s petition, nor were they able to produce their own estimates of the global population size based on the information available to them. NMFS also noted that while over 400,000 individuals of the A. percula/ocellaris complex were imported by the U.S. in 2005 (Rhyne et al., 2012), only a bit more than 200,000 fish of all species combined were imported from the countries in the range of A. percula (Australia, Papua New Guinea, Solomon Islands, and Vanuatu) with no indication that exports form these countries were heavily skewed toward A. percula, or any other species. Hence, NMFS concluded that imports of A. percula by the U.S. likely number fewer than 200,000 individuals per year, though they were not able to estimate the true number due to insufficient data. NMFS concluded that they were unable to assess the impact of the harvest of A. percula (totaling a maximum of ~200,000 individuals per year) on the status of the species.

Additional scientific data: The absolute levels of harvest of A. percula from the wild and their global population size are not precisely known. We simply don’t have sufficient data at this time to produce robust estimates of either of these parameters. Nonetheless, limited data are available which help us to produce rough estimates of harvest rates and global population size for the species.

First, the number of individuals of the A. percula/ocellaris complex imported into the U.S. in 2005 was a bit more than 400,000 individuals (Rhyne et al., 2012), and fewer than 200,000 of these were A. percula, though we don’t have a good estimate of the true level of import of this species in 2005 (Rhyne, pers. comm.). Based on unpublished data, Dr. Rhyne (pers. comm.) estimates that the number of anemonefish of all species combined imported to the U.S. has decreased over the last decade (likely in part due to higher rates of aquaculture of captive individuals) and totaled ~300,000 individuals in 2011. Dr. Rhyne estimates that in 2011 the number of Percula clownfish imported into the U.S. was on the order of 10% of the total number of anemonefish imported, or about 30,000 individuls. The U.S. is home to a bit more than 1 million of the world’s estimated 1.5 million marine aquarists, and consumes about 50-70% of the global trade in marine ornamental organisms (Tissot et al., 2010). Extrapolating the estimated rate of harvest of A. percula for the U.S. market (~30,000 individuals per year) to the global trade in the species suggests that the global, annual harvest of A. percula from the wild is likely on the order of 40,000-60,000 individuals per year.

Second, the global population size of wild Percula clownfish is challenging to estimate, though a few data are available which allow us to produce at least a rough estimate. Planes et al. (2009) examined population connectivity of A. percula in Kimbe Bay, Papua New Guinea. They report a population density of approximately 1200 adult A. percula per km2 of reef around Kimbe Island. Percula clownfish live in small colonies with a female-male pair occupying a host anemone, along with 0-4 juvenile fish. Hence, the population density of A. percula around Kimbe Island is likely on the order of 1200-3600 individuals (adults + juveniles) per km2 of reef. Elliot and Mariscal (2001) examined population structure, niche partitioning, and recruitment of anemonefish in Madang, Papua New Guinea, which has the highest species diversity of anemonefish (9 species) and host anemones (10 species) in the world. On these reefs the density of A. percula was highly variable depending on the reef zone (A. percula tended to be concentrated in shallower and lagoonal sites), but ranged from approximately 0-5.5 individuals per 100 m2, or 0-550,000 individuals per km2 of reef area. The overall, average density for A. percula on the reefs at Madang was approximately 0.83 individuals per 100 m2, or approximately 8300 individuals per km2 of reef area.


The natural range of Amphiprion percula.

Percula clownfish are found on reefs throughout Papua New Guinea, the Solomon Islands, Vanuatu, and northern Queensland, Australia (to about half way down the Great Barrier Reef, GBR). Spalding et al. (2001) estimated the area of coral reefs globally and split this information according to country. The coral reef areas for the four countries where A. percula are widely distributed are as follows:

CountryCoral reef area (km2)
Papua New Guinea13,840
Solomon Islands5,750

However, A. percula is currently distributed across only a portion of Australia’s reefs. The GBR constitutes more than half of Australia’s total reef area, and A. percula are distributed across the northern half of the GBR, as well as on other reefs around northern Queensland. Conservatively, I will estimate that A. percula are found on approximately one-quarter of Australia’s reefs (~12,240 km2) bringing the global reef area within the present-day distribution of A. percula to approximately 36,000 km2.

If we assume that A. percula has an average density throughout its range similar to the 1200-3600 individuals per km2 of reef area around Kimbe Island (Planes et al., 2009), then the global, wild population of A. percula is likely in the range of 43-130 million individuals. In contrast, if we assume an average density of 8300 individuals per km2 of reef area like that around Madang (Elliot and Mariscal, 2001), then the global, wild population of A. percula is approximately 300 million individuals. These areas provide excellent habitat for A. percula, and densities here may be higher than throughout much of the species’ range. For a conservative estimate of the global, wild population size we could assume that the average density of the species is only 10% of that measured around Kimbe Island and Madang, yielding a population size estimate of 4-30 million individuals. Therefore, depending primarily on uncertainties regarding their density on reefs across their area of distribution, I estimate that the global, wild population size of A. percula is very likely at least 4-30 million individuals, though the true population size may number into the hundreds of millions.

Natural mortality rates of A. percula in Madang are reported to range from 2% (Elliot and Mariscal, 2001) to 14% (Buston, 2003) per year. In these studies, mortality was fully compensated for by recruitment of juvenile fish, thereby maintaining a stable population size over the course of the studies. Rates of recruitment were strongly limited by intraspecific competition, rather than by the supply of larvae. That is, resident clownfish began to exclude new recruits as the number of resident fish in each anemone increased, but rates of recruitment increased by two orders of magnitude when resident clownfish were removed from their anemones (Elliot and Mariscal, 2001). Hence, habitat availability (i.e., the number of host anemones) and intraspecific competition place strong limits on A. percula recruitment in this area, rather than larval supply. If we assume a minimum, estimated global population for A. percula of 4 million individuals, these data suggest that approximately 80,000-160,000 juveniles would recruit annually across its range to replace individuals lost to natural sources of mortality. Potential rates of recruitment, however, would be on the order of 8-16 million individuals per year, assuming a global population size of 4 million individuals. If we assume higher population densities (like those around Kimbe Island and Madang) and a higher global population size, then realized rates of recruitment for A. percula may number in the millions of fish per year, with potential rates of recruitment ranging into the billions (far in excess of the environmental carrying capacity).

Given a minimum, estimated global population size of 4 million individuals, and an estimated potential recruitment rate of 8-16 million individuals per year, it is extremely unlikely that the annual harvest of 40,000-60,000 A. percula for the marine aquarium trade is a threat to the persistence of this species. In addition, little or no collection for the marine aquarium trade occurs across much of this species’ range, since many reefs where A. percula occur are included in Marine Protected Areas (e.g., significant portions of the GBR, along Australia), or because the reefs are extremely remote and far away from aquarium collection sites (e.g., much of Papua New Guinea; much of Northern Queensland, Australia).

While the estimates of global population size and annual recruitment rates I provide for A. percula here come with substantial uncertainties, these estimates nonetheless show that the global, wild population of A. percula is likely quite large and current levels of harvest for the marine aquarium trade almost certainly do not pose a threat to the species. Therefore, I argue that A. percula does not merit listing under the ESA based on this threat factor.


Threat factor E: Other natural or man-made factors affecting [a species’] continued existence.

CBD’s argument: The CBD cited a number of studies which show that many reef fish species show reduced aerobic scope, condition, growth, or survivorship under elevated temperatures, 1-3°C (2-5°F) higher than normal. [Note: seawater temperatures are expected to increase by 0.5-3.6°C (1-6°F) on coral reefs this century due to climate change. The magnitude of the temperature increase depends mostly on the quantity of greenhouse gases emitted by human activities (e.g., about 1°C under low emissions vs. about 3°C under high emissions), and secondarily depends on modest, regional variations in warming (e.g., 1.9 vs 2.5°C among different regions under moderate emissions).] Most of the references regarding the impacts of ocean warming in the CBD’s petition were general in scope, or were for species other than those which were petitioned (including both close relatives of the petitioned species, as well as distant relatives). In addition, the CBD cited studies which show that ocean acidification can impair the sensory systems of reef fish, including species-specific information regarding the Percula clownfish. Normally, fish larvae and juveniles swim toward the scents and sounds associated with appropriate habitat (for example, A. percula larvae normally swim toward the scent of host anemones and the sounds of a coral reef), and avoid the scents of unsuitable habitat and predators. By disrupting their sensory systems, ocean acidification can induce larval and juvenile fish (including A. percula) to avoid suitable habitat, and to swim toward unsuitable habitat and predators, which could reduce larval recruitment of a given species. The CBD argued that climate change and ocean acidification pose a threat to the petitioned species due to the direct, negative effects of these stressors on their physiology and recruitment.

NMFS’s response: NMFS largely rejected these arguments for the petitioned species, including for A. percula. In their finding, NMFS cited a number of studies (including those referenced by the CBD) which show that reef fish responses to elevated temperature vary substantially among species, including closely related species. In general, NMFS notes, species which tend to be thermal specialists and occur across relatively small geographic ranges, as well as those which are specialized toward cooler temperatures, tend to be less thermally tolerant than fish which are broadly distributed or occur over wider climatic gradient. Hence, different fish species can show highly divergent responses to elevated temperatures, even when they are found on the same reef in nature, and it is not clear that these species should be particularly vulnerable.


Percula clownfish. Photo by Jeff Kubina

NMFS also cited several studies which show rapid, trans-generation acclimatization to elevated temperature, ocean acidification, or both among some reef fish species. Likewise, they cite a study which shows significant variation in larval susceptibility to ocean acidification in the damselfish Pomacentrus wardi, which suggests the potential for rapid adaptation in response to ocean acidification. Little or no information was available to evaluate the potential for A. percula or the other fish species to adapt or acclimatize to future climate change and ocean acidification. Studies from a variety of reef fish species, including the few trans-generational studies which have been performed, suggest that some reef fish species have some capacity to adapt or acclimatize to future change, though this potential varies substantially and other species show little capacity to cope with future changes. Most of the petitioned species (with the exception of A. percula) have very broad geographic ranges, meaning that future changes in climate will not occur uniformly over the species’ ranges. While NMFS acknowledged the potential for climate change and ocean acidification to negatively impact the physiology and behavior of the petitioned species, they could not draw reasonable inferences about these impacts on the extinction risks for these species.

Additional scientific data: Overall, I agree with NMFS’s assessment here. Higher seawater temperature (due to climate change) and lower seawater pH (due to ocean acidification) clearly can and likely will affect the distribution and possibly the abundance of the petitioned fish species, as well as numerous other marine species. However, data which show trans-generational acclimatization and the potential for adaptation among some species suggest that many fish likely will survive in the warmer, more acidic ocean they will face this century, and there is little reason to think that the petitioned species are particularly vulnerable. Studies similar to those cited by NMFS and including additional fish species have recently been published which reach similar conclusions. Species are not created equal, and some appear to be much more susceptible to climate change and ocean acidification than others, but I agree with NMFS that there is little reason to conclude that these threats pose a clear threat of extinction for any of the petitioned species, including A. percula.

I will mention one additional study which I believe has bearing on this topic. Much of the important work published to date examining the effects of ocean acidification on fish sensory systems has been conducted by researchers working in the laboratory of Dr. Phil Munday. Prior to these publications, many of us in the research community (myself included) assumed that fish would be relatively unaffected by ocean acidification. Thanks to the pioneering work of Danielle Dixson, Phil Munday, and others it is clear that our assumptions were very wrong. Indeed, many fish are negatively affected by ocean acidification, as has been shown convincingly for numerous species, and as discussed above. Out of necessity, most experiments to date have been conducted in the laboratory where future ocean chemistry can be simulated. Where possible, it is always very useful to test the results of laboratory experiments in the field.

Off of a few small islands in Papua New Guinea there are natural, volcanic, carbon dioxide seeps. The carbon dioxide gas bubbles up from the sea floor, giving the area the appearance of champagne, and acidifying the sea water in the process. While these seeps are not a perfect analogue of future ocean acidification, they are still very useful for studying the effects of ocean acidification on reef organisms. Munday et al. (2014) set out to test the results of their laboratory experiments at these seeps. They report that fish captured at the seeps show the same behavioral impairment as fish examined in the laboratory (swimming toward the scents of predators, and showing no preference for appropriate habitat), and differ sharply in their behaviors as compared to fish collected on control reefs only a few hundred yards away. Contrary to expectations, however, there was no significant difference in the abundance, species diversity, or fish community structure at two of the three seep sites as compared to those at nearby control sites. At the third site the overall fish abundance and species diversity were similar between the carbon dioxide seep and the control reef, but the fish community structure differed between the acidified and non-acidified reefs. Rather than a direct effect of acidification, this difference in fish community structure appears to be a response to differences in the coral communities on each reef. At the carbon dioxide seeps, mounding Porites corals begin to dominate and branching coral species become much less common. Some fish species increase in abundance in concert with these changes in the coral communities, whereas other fish species decreased in abundance.

Threats to host anemone are a potential threat factor to clownfish.  Photo by Samuel Chow.

As above, these carbon dioxide seeps are not a perfect analog of ocean acidification, but they are still useful. In spite of impaired sensory systems, ocean acidification at these locations appears to have little or no effect on the abundance or composition of the reef fish communities. On the one hand, these results may paint a rosier picture than what will occur in the real world under ocean acidification. At this location reef fish larvae are produced in huge numbers on the abundant reefs and only a tiny fraction settle to the reefs in the seeps. Under ocean acidification, which will change seawater chemistry globally, the negative effects on fish behavior may start to manifest into significant reductions in recruitment, negatively affecting fish populations. On the other hand, because most of the fish larvae are settling to the seep sites from parents that are adapted and acclimatized to present-day seawater chemistry, there is little or no opportunity for trans-generational acclimatization or adaptation to be realized here. Hence, future fish communities may be as diverse and abundant as they are now, and the resident fish might show relatively less impairment of their sensory systems if they can adapt or acclimatize to changing ocean chemistry. Regardless, this study suggests that even when fish are behaviorally impaired by ocean acidification, the impairment may not actually translate into reduced population sizes.

Together, these various lines of evidence suggest that many fish likely can show some degree of adaptation or acclimatization to climate change and ocean acidification, though these potentials vary dramatically by species. The potential for A. percula to show an adaptive response to these changes is poorly understood, but I agree with NMFS that it is not clear that these threats are likely to lead to the extinction of the species. Therefore, I argue that A. percula does not merit listing under the ESA based on this threat factor.


Threat factor A: Present or threatened destruction, modification, or curtailment of [a species’] habitat or range.

CBD’s argument: The CBD argued that climate change threatens the critical habitat of the petitioned species, namely live corals for the damselfish species and anemone hosts for A. percula. They cite a number of studies showing that host anemones are susceptible to bleaching, which can reduce the abundance and size of the anemones and results in lower abundance of anemonefish due to a reduction in their critical habitat.

NMFS’s response: In their finding NMFS acknowledges that bleaching due to elevated seawater temperatures can reduce the size and abundance of host anemones, leading to reductions in the population size of A. percula. Further, NMFS notes that the geographic distribution of A. percula is much smaller than the other petitioned species, and the Coral Triangle area of the Western Pacific Ocean (which includes much of A. percula’s geographic distribution) is a climate change hot spot, with higher projected rates of warming as compared to some other coral reef regions. Due to the likely, negative impacts of climate change on A. percula’s critical habitat (host anemones), and the likely high level of exposure to ocean warming over much of its range, NMFS concludes that A. percula may warrant listing under the ESA as a consequence of these risks.

Additional scientific data: I concur with the CBD’s and NMFS’s assessment that climate change poses a risk to A. percula by imperiling its critical habitat of host anemones. Indeed, anemone bleaching does negatively impact both anemones and anemonefish, and part of A. percula’s current geographic distribution is within a climate change hot spot where relative rates of warming are likely to be particularly high. I feel, however, that two additional pieces of information should modify the conclusions drawn from these lines of evidence, and feel that this additional information suggests a lower risk of extinction for A. percula.

First, climate change and ocean acidification are occurring concurrently. Climate change is driven by human emissions of greenhouse gases and other substances which change the radiative balance of the planet, but chiefly by emissions of carbon dioxide. Ocean acidification is driven almost entirely by human emissions of carbon dioxide. The effects of ocean acidification on host anemone species has not yet been examined and is unknown, but the effects on other soft-bodied anthozoans have been investigated. Suggett et al. (2012) report that the anemone Anemonia viridis increased in size and doubled in abundance at carbon dioxide seeps in the Mediterranean (at carbon dioxide concentrations which could occur later this century due to ocean acidification) relative to their size and abundance at nearby control sites. This anemone species appears to benefit from ocean acidification due to a fertilization effect of higher carbon dioxide concentration on its endosymbiotic algae. Likewise, Inoue et al. (2013) report a dramatic shift from hard coral to soft coral dominance along a carbon dioxide gradient at a carbon dioxide seep in Japan, and that photosynthesis in the soft corals was enhanced by higher carbon dioxide concentration. While the effects of ocean acidification have not been investigated for host anemone species, the emerging picture is that soft-bodied anthozoans such as anemones and soft corals can benefit from ocean acidification due to enhanced rates of photosynthesis. It is unclear how host anemones will react to the combined effects of ocean warming and ocean acidification, but the studies above were conducted with ecologically and physiologically similar species and suggest that it is not straightforward to conclude that host anemones will decline in size or abundance under global change. By enhancing photosynthesis and growth rates, ocean acidification may at least partially offset the negative effects of ocean warming and bleaching on host anemones, A. percula’s critical habitat. If host anemones are able to tolerate climate change through some combination of adaptation, acclimatization, or latitudinal migration, it is even possible that their numbers could increase over the long term in response to ocean acidification.

Second, recent work has shown that rates of ocean warming due to climate change will be particularly high in the Western Pacific Warm Pool and parts of Melanesia (Teneva et al., 2012; van Hooidonk et al., 2013), which includes a portion of A. percula’s geographic distribution around northern Papua New Guinea and the Solomon Islands. This same work, however, shows that rates of warming and the incidence of high-temperature stress will be less severe along southern Papua New Guinea, Vanuatu, and particularly around Queensland, Australia. While the northern portion of A. percula’s range is within a climate change hot spot, climate change impacts are projected to be relatively less severe throughout the southern portion of its range. offers projections of future changes in fish abundance and distribution.’s model does indeed predict a reduction in the abundance of A. percula in the northernmost part of its range and an increase in abundance in the southern portion of its distribution, consistent with projected climate change impacts. In addition,’s distribution model projects a substantial southward expansion in A. percula’s range, extending to the southern GBR. While relatively simplistic, the projections from this model are certainly possible. Appropriate, anemone habitat already exists further south along the GBR than A. percula’s current distribution, facilitating latitudinal migration of the species. In addition, A. percula in Kimbe Bay were able to successfully recruit to reefs 15-35 km away from their home reef (Planes et al., 2009) and A. percula are able to reach sexual maturity within 2 years, suggesting that rates of southward migration as high as 1000-2000 km per century are plausible. Together these lines of evidence point to a shift in the distribution and geographic range of A. percula under climate change, and imply persistence rather than extinction of the species.

Climate change clearly poses a threat to A. percula’s critical habitat (host anemones) throughout at least a portion of its range and may lead to reduced abundance of the species in these areas. Host anemones, however, likely have some capacity to respond to climate change through a combination of acclimatization, adaptation, or latitudinal migration, they will be exposed to relatively lower climate change impacts throughout the southern portion of their native range, and A. percula likely will expand its distribution southward to appropriate, anemone habitat as the climate warms. For these reasons, I feel that it is unlikely climate change will imperil A. percula’s critical habitat such that the species becomes endangered or extinct over all or a significant portion of its range in the foreseeable future. Therefore, I argue that A. percula does not merit listing under the ESA based on this threat factor.


Threat factor D: Inadequacy of regulatory mechanisms.

CBD’s argument: As above, the CBD questioned whether current management practices associated with collection for the marine aquarium trade are adequate to safeguard A. percula or the other petitioned species.


Captive breeding of a variety of clownfish, including A.percula.  Photo by ‘stapp’

NMFS’s response: Due to a lack of data regarding the global population size of A. percula, NMFS was unable to address whether or not current management practices are likely to lead to overharvest. Because NMFS found that substantial information was presented regarding the threat of climate change to A. percula’s critical habitat, they determined that additional evaluation is required to determine whether or not current regulatory mechanisms are adequate to cope with this threat.

Additional scientific data: The regulatory mechanisms regarding the potential overharvest of A. percula for the marine aquarium trade and climate change impacts on A. percula’s critical habitat can only be inadequate if these threats pose a reasonable risk of causing A. percula to become endangered or go extinct across all or a significant portion of its range in the foreseeable future. As I have argued above, I believe that the best available science shows that neither of these risks pose a sufficient threat to A. percula that it will become endangered or go extinct in the foreseeable future. Therefore, I argue that A. percula does not merit listing under the ESA based on this threat factor.


Conclusion: What aquarists can do

I strongly agree with the CBD and NMFS that climate change and ocean acidification pose very real threats to A. percula (and many other marine organisms), but based on the best available science, I argue that these threats are unlikely to cause the species to become endangered or go extinct across part or all of its range in the foreseeable future, and that the species does not warrant listing under the ESA. It is possible for reasonable people to disagree with me here, and I’m quite sure that reasonable people do disagree with me. Nonetheless, I believe that the science is on the side of rejecting the CBD’s petition to list A. percula under the ESA.

The primary question NMFS is tasked with answering is whether or not A. percula warrants listing under the ESA. If they determine that the species does warrant listing, they must then determine if the species should be listed as threatened (which would imply a reasonable likelihood of becoming endangered in the foreseeable future) or as endangered (which would imply a reasonable likelihood of going extinct in the foreseeable future). If NMFS determines the species should be listed as threatened, they must then determine whether or not a 4-d rule banning take should be enacted to protect the species. It is possible that NMFS could enact a 4-d rule which would ban take across A. percula’s native, geographic range, but not extend the same protections to captive bred individuals in the U.S.  (under the Distinct Population Segments part of the clause), if doing so would not benefit recovery of the species, but would cause unnecessary hardship to stakeholders.

Regardless of your position on the proposed listing of the Percula clownfish under the ESA, I strongly encourage you to submit testimony to NMFS if you feel inclined so as to help them make the best-informed, most scientifically accurate assessment possible. Written testimony can be submitted online to NMFS here and must be received by November 3, 2014 11:59 PM ET.

I hope that with this pair of articles I was able to improve your understanding of how the Percula clownfish came to be petitioned for listing under the ESA, the process involved in listing a species, and the science surrounding this complex issue.



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  • Chris Jury

    I grew up in Michigan, hunting turtles, frogs, and other wonderful, creepy things. In high school I became particularly interested in coral reefs and set up my first reef tank in 2001--a modest 10 gal tank. I soon upgraded that tank and, as they say, the rest is history. I'm currently a Ph.D. candidate in biological oceanography at the University of Hawaii at Manoa where I investigate coral calcification and coral responses to global change.


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