Emptying Oceans

The status of marine vertebrates can be considered the unsung conservation crisis of our time with little be advertised on all media types about population declines or highlighting vulnerability. Such publicised conservation efforts are reserved for other terrestrial animals such Amur leopards, Giant Pandas or global ecosystems such as the amazon rainforest. In part this can be contributed to our empathy towards are fellow terrestrial organisms but ultimately it come down to what we can actually see, and in this case what is happening below the surface largely goes unnoticed. Some of this lack of public knowledge could be associated with the save the whale conservation actions of the mid 70's where there was public outcry over Japanese and worldwide whaling activities, though it seems that the public has considered this problem “Resolved” and cetaceans no longer under threat due to strict controls on whaling or the lack of participating countries. Or the belief the ocean inhabitants are capable of buffering against our harvesting techniques. This is not the case with the large percentages of marine vertebrates classed within higher levels of vulnerability according to IUCN, or even larger percentages of species classed as data deficient due to the inability to monitor them or the lack of funding opportunities due their lack of commercial value. 

Referring back to status of marine vertebrates, marine mammals in particular it has been estimated that ¼ of all marine mammals are classed as vulnerable with an even greater number classed as data deficient 35% to be exact. This severity of vulnerability is large associated with our negative impacts upon the oceans such as increased nautical activities such as shipping and large unknown effects of sonar, but the biggest threat of all is that of fisheries bycatch. An example of species decline ads a result of past human exploitation is that of the Northern Right whale, who's populations are believed to be as fewer than 300 individuals and was classed as nearly reproductively extinct in the wild in 2008 IUCN Red List publication (Fujiwara & Caswell,2001). In contrast the Amur leopard population is said to be just a handful of individuals though this receives global funding and coverage? Following that of marine mammals which have greatest source of empathy than any other, is a taxon containing some of the most important apex predators of the seas, this being sharks and rays elasmobranchs.

Squat-Headed Hammerhead Shark, Endangered,
 Decreasing Population.

The severity and general vulnerability to this species is severe with 47% data deficient with a further 17% threatened and 13% near threatened.  The greatest risk that elasmobranchs are faced with is that of bycatch and over fishing. With large number of sharks annually being harvest for finning to sustain an increasing unsustainable demand in the Far East. Such is illustrated within all 7 sawfish species which are classed as critically endangered as a result of fishing pressures for their desirable saw “noses”.  This vulnerability of sharks is even greater within a regional scale with large pelagic predators nearly extinct from certain parts of the world. One of the most documented shark populations is that of the North West Atlantic, though this in itself is a result of its intense lone line fisheries but has allowed population changes to be estimated since 1986 (Baum et al.,2010). Within the North Western Atlantic species have declined 50% overall within an 8-15 year period, with certain species suffering the brunt. This is illustrated in the hammerhead shark suffering a decline of 89% since 86’, followed by Great white sharks populations decline 79% since 89’ though this is twinned with a greater decline in catch encounter of 80% indicating that the population decline could In fact be significantly more severe .  Though such a study only illustrates a single corner of the globe, its high intensity fisheries could be extrapolated worldwide to similar intensity areas or scaled down to fit less fishery intense areas, allowing global population declines to be estimated.

Hong Kong Grouper, Endangered,
Decreasing population.

Following elasmobranchs is that of bony fish, the second largest taxon on earth second to that of invertebrate life and potentially the most understudies and most commercially exploited. The severity of the exploitation is illustrated with the figure of only 6% out of 15,500 fish species assessed under the IUCN Red List, with the documented decline of 83% on those species that are commercially exploited over the last 2-3 decades (Reynolds et al., 2005). Though the lack of study can be contributed to the difficulty of studying these highly pelagic and migratory species therefore the feasibility is greatly reduced, meaning regional studies have greater influence. Such regional examples include the great mass extinction and exploitation of North Atlantic Cod in Cape Cod, resulting in the collapse of the fisheries and closure of fishing grounds. Subsequent closure was used to allow populations to recover; recent scientific long lining resulted in the capture of just 2 Juvenile cod in 10,000 hooks following a period of 20 years of fishing restrictions. Similarly studies within Flamborough head Cod populations were estimated to sustain number of 3.1million individuals, but forecasted populations only accounted for 121 individuals (Reynolds et al., 2005). Further highlighting the plight of commercially fished species is that of the grouper. Groupers are high desirable and significantly over fished to reach growing Asian demands. Annually 250,000 tons of grouper is fished, across all its life stages due to the demand and the capabilities of captive maturation, reaching demand imposed by the Asian live reef fish food trade. This over exploitation has ultimately results in 12.4% of the 161 grouper specie being classed as threatened and 30% classed as data deficient (IUCN, 2008).

Supporting large numbers of species and a potential keystone in marine ecosystems is that of coral reefs. These are high sensitive species suffering from numerous anthropogenic threats such as ocean acidification, over harvesting or climate change. This has resulted in 27% of 845 skeletal forming corals to be classed as threatened with a further 17% data deficient (IUCN, 2008). In hand with Corals is the decline of worldwide Marine Turtle populations with 6 out of 7 species being classed as threatened with one the Australian endemic Flatback Turtle classed as data deficient. Issues surrounding that of marine turtles are that of whether population should be subjected to global endangered statuses or regional ones, as many populations are isolated and rarely interact with one another. Once such example can be that of the Green and Loggerhead Turtle populations in the Mediterranean.

Amsterdam Albatross, Critically Endangered,
Decreasing Population.

Lastly is the status of Seabirds. Seabirds are one of the most heavily studies groups of all marine vertebrates resulting in only 1% classed as data deficient. Though these species are intensely studied it suffers greatly from a number of threats due to split between aquatic and terrestrial life stages, resulting in 27.5% classed as threatened. Though this number is high certain species are more threatened than other due to differing life history traits, one such example are the captivating albatross species. Albatrosses can be considered the most threatened of all bird species with 89% (19 species) listed at critically endangered with further estimated population declines of 80% over the next 3 generations.







References:

• Baum JK., Myers RA.,Kehler DG., Worm B., Harley SJ., Doherty PA. 2003.Collaspe and Conservation of Shark Popiltaions in the Northwest Atlantic. Science, 299, 389-391.

• Fujiwara M., Caswell H., 2001. Demography of the endangered North Atlantic right whale, Nature, 414,537-540.

• Reynolds JD., Dulvy NK., Goodwin NB. Hutchings JA., 2005. Biology of extinction risk in marine fishes. Proceedings of the Royal Society Biology,272,2337-2344.

• Polidoro, B.A., Livingstone, S.R., Carpenter, K.E., Hutchinson, B., Mast, R.B., Pilcher, N., Sadovy de Mitcheson, Y.and Valenti, S. 2008. Status of the world’s marine species. In: J.-C. Vié, C., Hilton-Taylor, and S.N. Stuart (eds.).The 2008 Review of The IUCN Red List of Threatened Species. IUCN, Gland. Switzerland.

Animal "Guess Who"

Typical Photo ID in Cetaceans

The use of photographic individual recognition is commonly associated with cetacean research and allows the identification of individuals or entire pods through the use of creating dorsal of fluke libraries allowing subsequent picture comparison. The benefit of such systems is due to the use of key body structures such as notch's, scars and defining features that allows individuals to be recognised. It has long been known that dorsal fins and flukes can be used in individual recognition due to equivalent fingerprint quality. This has therefore allowed individuals to be tracked and re-identified throughout the globe via these libraries highlighting huge migratory patterns undertaken by large marine vertebrates. Examples of photo libraries exist within almost all major cetacean research groups including that of Sea Watch situated within Cardigan Bay and also that of hebridean whale and dolphin trust. Though such a technique is applied to cetaceans and its application within other marine animals is growing due to its un-invasive application and growing reliability in comparison congenital tags that have high failure rates. Recent studies have been conducted on Whale sharks and Loggerhead turtles to establish its viability as a recognition device and population estimate technique.

Whale Shark Individual Spot and Stripe Markings

The study looking at whale sharks was conducted at Ningaloo Reef Western Australia (Meekan et al., 2006) which has annual whale shark aggregations and allows the opportunity to formulate population estimates and sex ratios from these large highly migratory pelagic species. Similar to that of dorsal fins whale sharks have individual spots and striped markings behind the gills allowing for individual recognition, similarly the usage of prominent scars and fins is additionally used. The study illustrates 100% success rate with the use of high quality pictures and highlights the role that tour operators can have in providing images in to aid in conservation efforts though the study did depict the need of some training aspect to ensure viable photos.  Key findings within the study illustrates predominately make biased sex ratios within the population visiting Ningaloo Reef in addition to highlight migratory pathways undertaken by certain individuals due to both subsequent annual visits and visits involving large time scale breaks. Similarly the areas of further investigation is that of the coupling of worldwide or even region photo data bases that could allow the mapping of migratory routes and through the use of pop-up tags could allow potentially entire migratory pathways to be mapped which has been previously been attempted in other pieces of research (Eckert et al., 2002)

The second trial was looking at the use of facial (post-ocular) scales to identify turtles in a non-invasive way whilst scuba diving or snorkelling through photo identification, allowing for the collection of population estimates separately from just laying females. This trial study illustrated clear positive possibilities in the identification of non-nesting females and illusive males to be added to population and sex ratio estimates. It was illustrated that 100% matching was achievable  within a 400 individual data set through trained observers and that positive matching could be enhanced through the use of short training sessions given to untrained observed/volunteers (Shofiled et al.,2008).

Facial Scale Recognition in Logger Head Turtle Carreta carreta

References:

Eckert SA. Dolar LL. Kooyman GL. Perrin W. Rahman RA. 2002. Movements of whale sharks (Rhincodon typus) in South- east Asian waters as determined by satellite telemetry. Journal of Zoology, 257, 111-115.

Meekan MG. Bradshaw CJ. Press M. Mclean C. Richards A. Quasnichka. Taylor JG. 2006. Population size and structure of whale sharks Rhincodon typus at Ningaloo Reef, Western Australia.Marine Ecology Progress Series, 319, 275-285. 

Schofield G. Karselidis KA. Dimopoulos P. Pantis JD.,2008. Investigating the viability of photo-identification as an objective tool to study endangered sea turtle populations. Journal of Experimental Marine Biology and Ecology, 360,103-108.

http://www.seawatchfoundation.org.uk/

http://www.whaledolphintrust.co.uk/

Eye spy with my little eye, something beginning with "W"

Aerial surveying is one the many survey techniques that can be employed to assess marine population sizes, distribution and potential changes. There are both benefits and negatives associated with such a surveying techniques and room for improvement also.

Aerial Surveyors 

One of the major benefits associated with such a technique is its capability if reaching isolated nesting beaches and haul out sites without causing unnecessary stress upon animals through human interference. Such techniques of using aerial surveys are commonly employed through the use of either observers or high quality digital photography allowing for the checking of sightings and confirmation of species observed. Such as technique has been recently employed in the survey of Antarctic minke whales which distribution is large and irregular and is sometime difficult to locate amongst the pack sea ice (Kelly et al., 2009). Though aerial surveying only compromised of a small proportion of the surveys overall, in this case it was undertaken alongside boat or fixed station observation areas where seasonal migratory passageways occur, but such techniques allow for individuals to be counted that could possibly be missed by other means.

Antarctic Minke Whale amongst Ice flow

 Similarly the deployment of aerial surveying is used in establish population numbers and is commonly associated with seals and other haul out species. Such examples include the monitoring of harbour seals on the Gulf of Alaska where repeated aerial survey occurred through the course of 1995-2000 to provide a running population estimates (Boveng et al., 2003) of its decline population. In the case of using aerial surveys for population estimates or even boat surveys for that matter consideration has to be taken in relation to accounting for the individuals that are out at sea and therefore where not included. Therefore correction factors (CF) are used to calculate the proportion of individuals that are likely not to have been observed. Such CFs can be obtained through the use of other similarly sized same species colonies or in some cases researchers have tagged small proportion of the populations and used this to calculate the missing percentage and extrapolate this upwards to produce and overall estimated number.

Though it seems aerial surveys have benefits in allowing the coverage of large or secluded areas quickly the major issue is that of cost with such techniques being largely expensive. On the other hand in light of rapid technological advancements latest aerial surveys can be undertaken through the use of high quality satellite photography allowing near precise population estimates. Such a technique has been used in the surveying of emperor penguins by the British Antarctic Survey and collaborators, where computer imaging software is able to be programmed to differentiate between individual penguins, neighbours and ice and poo.

Satellite Photography of Emperor Penguin Colony

Unravelling Worlds

With the rapidly decreasing costs when it comes to satellite tracking animals, the opportunity to study great migrations is becoming more cost effective and accessible. Allowing insights into the previously uncharted territories’ and investigating the behaviours and distribution of animals on a global scale. Such projects are common in establishing the migratory routes of animals or establishing keys area that are in need of conservation attention. With the reduction of cost in equipment, the main restricting factor has always been the ethics of tagging, but this in turn has become more accepted due to technological advancements. This is mainly down to the reduction in size of the actual transmitters with them becoming less invasive and possessing negligible or no negative side effects to test subjects.

The dramatic reduction in transmitter size can be seen in the recent publication looking at the tracking of juvenile Loggerhead turtles Caretta caretta as young as 6 months old off the coast of South East America. Small tracking devices typically weighing less than 9gm and usually used for bird tracking were adapted for this special aquatic role. In this endeavour 17 turtles were tracked at a cost of £32,000, exposing a 4500 journey through the Caribbean and up into South American Eastern Coast.  Such use has shed light on the ever wondering question of where do juvenile turtles go once then leave the nesting beaches? What do they do? With such project leading the way for future projects on other marine vertebrates through the use of such techniques can only be assured.  

Though the reduction in cost when it comes to satellite tracking is positive steps, one of the major downside has always been tag retrieval with pieces of kit falling off and expensive kit being irretrievable. Surely the next logical step will be to produce tags that are easily obtainable after detachment allowing for further reduction in cost?

   Juvenile Loggerhead Caretta caretta with Satellite Tag.

With the reduction in tag size the issue of employing them in the field is greatly reduced. With the need for satellite tracking in all genus’s, the role in which such endeavours have in allowing individuals to be tracked for long periods of time, highlighting key feeding areas and nesting beaches in migratory patterns is beyond monetary restraints.

I again refer back to a marine turtle example, this time looking at the tagging of the endemic Flatback Turtle of Northern Australia and the indo pacific. This species suffers from a large collection of human impact from beachside development, habitat degradation, by-catch and pollution. 

Ultimately the study of loss of nesting beaches has severe hamperings on population growth and success, though the identification of key adult feeding grounds and the protection of both feeding grounds and nesting beaches are essential to ensure their survival. This is where tracking comes into play. Since 2005 Flatback turtles have been tracked annually identifying key areas of adult activity of which has never been identified.  This has been essential post and pre migratory breeding feeding locations, in this case seagrass beds. Which in turn need conservation, long term study projects to monitor and document the damage that is to come with climate change. 

Flatback Turtle Natator depressus With satellite tag

Such projects are essential for such species which are classed as data deficient and require further study looking at population health and fluctuations. In the light of climate change and increasing human encroachment such studies have never been so important.  Though I have focused on Marine Turtles, tagging is wildly used on other terrestrial and marine animals, ranging for whale, fish, antelopes and birds, with an array of tags used, of which I plan to cover at a later date.

An intersting current terrestrial study in progress is being conducted  by BTO looking at the migratiory routes of 5 Cuckoos whos annual winter migration to central africa and back again to the UK is for the first time being documented. The progress of each indivual can be viewed and explored on their website http://www.bto.org/science/migration/tracking-studies/cuckoo-tracking.