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Conservation of Amsterdam Albatrosses

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By Samantha Owen, RJD Intern

This paper outlines the current conservation efforts for the Critically Endangered Amsterdam albatross (Diomedea amsterdamensis) and the threat posed by industrial longline fisheries. In 2007 a population survey estimated that there were only 167 Amsterdam albatrosses in the world.  This is largely because they are only found in one place, Amsterdam Island, in the southern Indian Ocean.  Their population declined dramatically in the 1960s and 1970s due to the increase in industrial longline fishing targeting bluefin tuna.  While diving below the surface of the water when feeding, birds can be accidentally hooked or entangled in the longlines.

Like most albatrosses, this species is a biennial breeder, which means they only breed every other year. In between breeding years, they spend the entire break year roaming at sea.  A successfully mated pair will produce only one egg per breeding year.  This means that with such a small population, any mortality could have a huge impact on the viability of this species.  The established threshold to trigger a population decline is a loss of more than six individuals to bycatch per year. The potential number of individuals removed from the Amsterdam albatross population each year due to longline fishing is 2-16 depending on whether mitigation measures such as tori lines, plastic streamers trailing from the back of the boat used to scare birds away, were systematically employed.

amsterdam albatross

This paper quantifies the potential threat from industrial longline fishing fleets to the Amsterdam albatross based on time of year and life stages.  It shows that even though the Amsterdam albatross is potentially in contact with longline fisheries at every stage of its life, non-breeding individuals have a much higher susceptibility due to their significantly increased roaming area during their break year at sea. The time of year when Amsterdam albatrosses are at the highest risk for mortality as a result of bycatch in longlines is the austral winter (July, August, September) when fishing fleets are targeting albacore and other tunas.

The Taiwanese longline fishing fleet poses the greatest threat to Amsterdam albatrosses, followed closely by the Japanese fleet. One reason it is thought that the Taiwanese fleet has such a high impact on the Amsterdam albatross is because they deploy the most longlines in the waters immediately adjacent to the species’ home, Amsterdam Island.

In conclusion, this paper states three recommendations for further conservation efforts. First, increasing the coverage of fishing operations by dedicated observers in the distribution range of the Amsterdam albatross during the austral winter.  This would ensure the successful implementation of bycatch mitigation measures such as tori lines. The second recommendation is for Regional Fisheries Management Organizations (RFMOs) such as the Indian Ocean Tuna Commission (IOTC) to require all operating vessels to report ring recoveries.  All Amsterdam albatrosses have been fitted with leg bands (rings) identifying each individual. Although it would not directly prevent bycatch, reporting all recovered rings would allow scientists to more accurately define population-specific bycatch patterns in regional areas resulting in more targeted conservation efforts.  The third recommendation is to implement regulations on fishing efforts in the waters surrounding Amsterdam Island during the austral winter.  The combination of these three conservation efforts would allow the world’s only population of the Amsterdam albatross to grow and prevent any further decline that might very well result in the extinction of the species.

 

References:

Thiebot J.B., Delord K., Barbraud C.B., Marteau C., Wemerskirch H. 2015. 167 individuals versus millions of hooks: bycatch mitigation in longline fisheries underlies conservation of Amsterdam albatrosses. Aquatic Conservation: Marine and Freshwater Ecosystems. DOI: 10.1002/aqu.2578

Towards more efficient longline fisheries: fish feeding behavior, bait characteristics and development.

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By Sarah Hirth, RJD Intern

There has been a growing demand for bait resources seeing that standard bait types, such as squid, herring and mackerel are also used for human consumption. As a result, bait prices have increased, thus increasing the demand for an alternative bait, one that is not based on resources used for human consumption. This study highlights factors that need to be taken into consideration when looking for alternative bait, and explores attempts of alternative baits that have been made.

Løkkeborg at al. agree that an alternative bait should be “effective, species- and size-selective, practical for storage and baiting, and based on low-cost surplus products.” An alternative bait that would meet all of these characteristics would also make the procedure of longline fishing more environmentally friendly.

Although there have been several attempts to develop alternative baits, these have had limited success (e.g. Bjordal and Løkkeborg 1996; Januma et al. 2003; Polet al. 2008; Henriksen 2009). There have been two main methods, which have been used to create the alternative bait. These are natural resources, such as surplus products from the fishing industry and synthetic ingredients as attractants. Mentioned types of alternative bait are: Norbait, artificial bait invented by William E.S. Carr, bait bags, and arom bait.

Table 1

When these baits were tested, they all resulted in some positive factors. However, they still had undesirable outcomes. For example Norbait, which is based on surplus products, where minced fish products are mixed with alginate (a gelling agent, used as the binder) and extruded into a fiber mesh tube, has resulted in species –selective effects. In fishing trials Norbait has resulted in increased catch rates of two to three hundred per cent for haddock, yet Norbait compared poorly to natural bait for cod. “Compared to natural bait, minced herring enclosed in a nylon bag resulted in a 58% higher catch rates for haddock, a non-significant catch increase for tusk and ling, and a considerably lower catch rate for cod.” Similar results were observed with the other types of alternative baits.

The efficiency of longline baits depends on several factors, which are important to take into consideration when finding alternative baits. Some factors include: bait size, texture, and taste. An alternative bait also needs to be based on an odor source, and attractants need to be released over a considerable period of time. Løkkeborg et al. state that “the knowledge of food search behavior in fish is the basis of bait development efforts.” The list of factors affecting feeding behavior in this review includes: temperature, feeding motivation and hunger state, diel, tidal and annual rhythms, light levels, seasonal change in photoperiod, and water currents.

Figure 1

Although there currently are no alternative baits used in longline fishing, Løkkeborg et al. hope that improved knowledge of how fish respond to baited gear will aid future research aimed at the development of alternative baits. As the demand for marine resources for human consumption continues to increase, costs for longline bait are also likely to keep increasing. “The development of alternative baits used on resources not used for human consumption may therefore prove to be critical to a viable longline fisheries.”

Løkkeborg, S., et al. (2014). “Towards more efficient longline fisheries: fish feeding behaviour, bait characteristics and development of alternative baits.” Reviews in Fish Biology and Fisheries 24(4): 985-1003.