What happens when conserving an Endangered species impacts a fishery worth A$1 million?

Conservation efforts in many parts of the world are often impacted by money. This is not a reference to the usual lack of funding for the average not-for-profit - although that is an important side note - but the often lucrative reasons for why a species has fallen into decline in the first place. With rhino horn worth more than gold and a bowl of shark fin soup selling for up to HK$2000 there is a price on the heads of wildlife so high that it can offer some convincing reasons to some parties against supporting conservation efforts.

Financial implications of lost business are also of concern to the fisheries industry. Whilst sustainable fishing is, of course, important to the fishing industry as it translates to continued employment, closing a fishery to protect a non-target species can lead to socio-economic conflict between conservationists and fishers if the fishery in question also contains a valuable target species.

This is what happened in 2012 with the release of a management strategy for the upper slope dogfish in Australia. One species of upper slope dogfish - Harrissons Dogfish (Centrophorus harrissoni) - is classified as Endangered in the IUCN Red List and uses Taupo seamount off New South Wales as a refuge. The management strategy released in 2012 proposed a higher level of protection for Taupo seamount which would officially close it to all fishing activity, therefore protecting this vulnerable species.

The road to this proposed closure had been a long winded process; Harrisson's Dogfish was first nominated for listing under the Environment Protection and Biodiversity Conservation Act in 2005. Taupo seamount was then sampled and subsequently identified as a refuge for Harrissons Dogfish in 2009 and subsequently the seamount was closed to commercial fishing activity under the advice of the Australian Fisheries Management Authority (AFMA) in 2010.  

The closure of the fishery in this instance caused controversy as the seamount chain in question contributes 25% of the annual total allowable catch of Blue-Eye Travally (Hyperoglyphe antarctica). This is a fishery which has a total value of A$1million and so the closure would have had a significant impact on the lives of the fishers and the Australian economy. 

In 2015 the original closure and planned upgrading of the seamount to Marine National Park status was revised (AFMA Ecological Risk management 2015) to allow commercial line fishing around Taupo seamount. Whilst this may initially seem like a step backwards, the revision was undertaken with a view that the fishery could be compartmentalised to allow fishers to maintain their catch of Blue-Eye Trevally whilst not impacting the Endangered Harrissons Dogfish.

Harrissons Dogfish is a diel vertical migrator - the shark spends daylight hours at depths of >550m and ascends at night-time to feed on micronekton. Researchers at CSIRO and Australian Museum hypothesised that the seamount could potentially be open to line fishing above 550m; this would allow fishers to catch Blue-Eye Travally during the day but should not have any impact on the Harrissons Dogfish stocks.

The researchers carried out their own fishing effort around the seamounts, deploying fishing lines both during the day and at night as well as into the Mid (280-550m) Zone and Deep (550-830m) Zone. The results showed that catches of Harrissons Dogfish were avoided when fishing for Blue-Eye Travally at depths of 280-550m during the daytime, using standard commercial power handline. Whilst surveying the area, the researchers also discovered that the range inhabited by Harrissons Dogfish was much wider than previously thought.

These results were used to inform policy makers when finalising the management plan for Harrissons Dogfish. Whilst the zoning category of the Taupo seamount was relaxed to allow commercial handline fishing activities, the zoning category of the Derwent Hunter Seamount was increased and the Queensland and Britannia seamounts were included in the Commonwealth Marine Reserves network owing to the new evidence of Harrisons Dogfish in these regions.

The declassification of Taupo seamount from Marine National Park to Habitat Protection Zone is never a step in the right direction as far as any conservationist is concerned. However strict regulations are in place: the fishery is subject to 100% monitoring and if any vessels interact with more than 3 Harrissons Dogfish they will lose their rights to fish in the region for 12 months. In addition to this the removal of Harrissons Dogfish has been entirely prohibited.

So when conservation conflicts with huge financial profit can there be a happy medium? This solution may be a way to keep everyone happy; however the truth of the matter is that the only way we will known is by ongoing monitoring and sampling in the region to see if the populations of Harrissons Dogfish truly are unaffected by the Blue-Eye Travally industry.

The 2015 Worldwide Shark Attack Summary is out!

According to the 2015 Worldwide Shark Attack Summary of the International Shark Attack File (ISAF), 2015 saw a record high number of unprovoked shark attacks. Out of a total of 164 recorded attacks, 98 were categorised as unprovoked; this figure surpasses the previous highest number of 88 unprovoked shark attacks in 2000.

However, before you go grabbing your speargun and practising the line "Smile you son of a bitch", it's important to point out that whilst the number of unprovoked attacks has risen in 2015, the overall rate of attacks could very well have remained unchanged or even fallen. The researchers who curate the ISAF attributed the increase in shark attacks to more humans in the water and better reporting of shark attacks rather than an increase in the rate of shark attacks. The researchers also caution against putting too much faith in short term trends owing to year to year variability of environmental conditions which can affect shark populations.

Of the 98 unprovoked shark attacks in 2015, there were only 6 fatalities worldwide and long term trends indicate that the rate of fatalities owing to shark attacks is decreasing. Whilst news of shark attacks will always draw media attention and excitement, the numbers pale into insignificance when compared to the 1.24 million people who were reported to have been killed in road traffic accidents in 2010.

Geographically the majority of the shark attacks occurred in North American waters, with Australia coming a close second with 18 unprovoked attacks - 1 of which was fatal. People participating in activities which caused a lot of surface turbulence such as surfers were the most vulnerable to attack whilst snorkellers constituted only 9% of the number of people attacked. There were no reports of unprovoked attacks on scuba divers in 2015.

The ISAF has been run from the Florida Museum of Natural History since 1988 and is the longest running database on shark attacks globally. As well as curating worldwide shark attack information, the ISAF also provides regular advice on shark attacks issues.

Sustainability of shark fisheries on the Great Barrier Reef

The Great Barrier Reef Marine Park (GBRMP) is known worldwide as a natural wonder: a protected underwater haven for tropical fish, sharks and other marine fauna. However, only 33% of this marine protected area is closed to commercial fishing activities - within the rest of the park commercial fishing boats are allowed to operate and to carry out large scale fishing activities such as trawling and gill netting.

This is not to say that these activities are allowed to happen unchecked, however. Commercial fishing within the park operates under strict zoning rules and, as with most commercial fisheries there are maximum fishing quotas and possession limits in place.

The difficulty with any type of commercial fishing activity is assessing whether the existing marine populations truly can bear the brunt of the fishing activity. The ocean is a huge area and species are typically wide ranging, making accurate assessment of animal numbers difficult.    

In recent study published in Fisheries Research a team of researchers have discovered that some commercial fishing activities within the GBRMP may not be sustainable.

The study focused on tagging and assessing the three most commonly harvested sharks in the GBRMP: the Australian blacktip shark (Carcharhinus tilstoni), the Spot-tail shark (Carcharhinus sorrah), and the Spinner shark (Carcharhinus brevipinna). The Pigeye shark (Carcharhinus amboinensis) and the Australian Sharpnose shark (Rhizoprionodon taylori) were also included as two example of non-target species. In total, 3,413 sharks were tagged during the course of the study.

Whilst the team discovered that harvest rates were highest for the Pigeye shark it was summarised that the numbers were still around the acceptable optimal equilibrium harvest rate for this species. Only a small amount of the population of this stock were vulnerable to commercial fishing activity and therefore the species may be able to withstand greater fishing pressure. However such high harvest rates for this species are surprising as it is not a target species and is instead being caught as bycatch by fishing boats.

The more worrying outcome of the study was that whilst the annual harvest rate was lower for Australian Blacktip sharks than for Pigeye sharks, the current level of exploitation of this species could be too high. This is owing to 2 main factors: the population of Blacktip sharks in the GBRMP is thought to have a lower reproductive rate than populations from northern Australia making it more difficult for stocks to replenish themselves, and this species is available to commercial fisheries from age 0 meaning that all of the population can be fished at any stage of their life cycle.

Whilst these findings can only make assumptions about localised depletion of the study species within the GBRMP, the results are important and further research and monitoring is essential to ensure that fish stocks remain healthy in this marine protected area.      

Harry et al. (2016) Assessment of a data-limited, multi-species shark fishery in the GreatBarrier Reef Marine Park and south-east Queensland