July 1, 2010
By Stefan Thiesen
What is Bycatch? Is it a necessary evil of the fishing industry, or can it be avoided? What does it mean that we just throw away millions of tons of living beings? How can we change our global behavior and attitude towards the world that surrounds us?
1.1 - Bycatch - a short definition
"Imagine the meat in your supermarkets would be obtained by mass bombing the forests of the world and collecting whatever we find and need while simply discarding the rest and leaving behind nothing but burnt soil. This is more or less what we do to the sea.[i]"
(Master Makani in "Orcaworld")
According to the Lighthouse Foundation - a German not-for profit Marine advocacy organisation established by the City of Hamburg - more than 27 million tons of fish and other marine organisms are caught as bycatch and discarded each year. The numbers differ from source to source, but all in all roughly one third of the entire catch is bycatch and ultimately ends up as "discard", in other words: the caught animals are thrown over board and in most cases don't survive. Life animals are simply dumped for no particular reason. In part bycatch is the result of inappropriate and highly unselective fishing methods and equipment leading to indiscriminating fishing. The fishing areas also play a role as the makeup and behaviour of marine populations differ from region to region.
Bycatch is the sum total of all unwanted organisms that are caught. Aside from too small fish (for economic and legal reasons), this includes seabirds like Albatross and other gulls, as well as turtles, whales, dolphins and seals dying horrific deaths in nets, traps and on long line hooks. Historically bycatch - in the sense of discard - is a relatively recent phenomenon, as in older times in hunter/gatherer societies as well as in current subsistence settings all parts of a catch as well as all parts of an animal are used. Additionally traditional societies generally display some form of cooperative attitude towards the nature and its resources they live from, which leads to some form of combined economic and ecological behaviour - house-keeping with resources in the best sense of the word. Discard therefore was unknown. It is a by-product of modern economic processes and industrial fishing methods where it can be more "economically beneficial" to throw away large portions of a catch in favour of a limited number of target species - or even a single target species - of a higher monetary value. Extreme examples are shrimp fisheries, where the catch/discard ratio can reach 1:15, and approx. 16 million tons of traditionally defined discards result from Shrimp fisheries alone[ii].
Bycatch of Shrimp Fishing (Source: NOAA)
A less common definition of bycatch is the discard of sharks resulting from the practice of shark-finning, where the shark is, so to say, bycatch to itself. Estimates sharks killed in this process range from 26 million to 78 Million annually[iii]. Bycatch drastically aggravates the global overfishing situation and contributes to species decline, ecosystem shifts and environmental change on all levels.
1.2 Bycatch and Discard - Details of a Global Disaster
1.2.1 A complicated Issue
The problem has causes, reasons and implications on and in many interlocked levels and arenas, ranging from practical and technical aspects of fishing methods and methodologies over sociological, economical and philosophical/ethical topics all the way to the murky waters of international politics. The following are some fishing methods connected to bycatch.
1.2.2 Technology mesh sizes and dredging
The topic that is most easily addressed is technology improvement, especially since improved fishing methods and techniques in many cases not only significantly (sometimes drastically or near completely) reduce bycatch - they also have the side effect of reducing efforts for the fishermen and hence come with economic incentives attached to them. In any case avoiding or reducing bycatch required significant skills on the side of the fishermen and demands well thought through and excellently designed equipment. The type of bycatch also is a function of, among other factors, the setting of the fishing gear and the respective sea floor composition. Necessary know how on the side of the fishermen includes fisheries biology. They must have regional knowledge of species distribution as well as preferred spawning grounds and location of young fish stocks. It is common knowledge among men of the craft that fish below a certain size - Haddock under 25 cm and Cod below 35 cm had not yet spawned, and every fisherman knows how to handle his nets and gear to catch fewer small fish - fish he now would discard and that would later be missing as part of his valuable catch. The most common method to control the catch is by varying the mesh sizes. Increasing mesh sizes reduces bycatch of smaller fish while decreasing it increases it, up to the level where practically everything in the way of the net is caught, which is, for example, the reason for the enormous amounts of bycatch in classical shrimp fisheries. Such fine meshed nets result in a catch of up to 90% undesired species, derogatively called "trash fish", which generally is thrown over board due to its low economic value in comparison to shrimp.
The main method applied in shrimp fisheries and bottom ìharvestî of sea food - such as shells and bottom dwelling fish - is dredging. Dredging not only catches practically everything alive in, on or near the sea floor, it also strongly impacts the habitat itself by literally ploughing the surface. The true impact of this practice on benthic communities and beyond is difficult to assess, since the knowledge about marine habitat variability is scarce. However, in a long term experimental study of scallop fisheries comparing dredged to non-dredged sea floors in Port Phillip Bay, Australia, [Currie and Parry ,1996] have found that even 14 months after the last dredging event occurred, some benthic species had not yet recovered. The result is a change in community structure of the benthos. The same research also indicated that changes by community structure were below the natural seasonal and weather event induced variation[iv]. At first site this appears to be an encouraging result, but since the overall sensitivity of benthic ecosystem over longer periods of time is poorly understood it is difficult to assess such results in terms of an environmental impact statement. Small impacts significantly below natural variation can still be a strong enough signal in a dynamic system to result in significant changes all the way to collapse. It is common knowledge in ecology that diversity is a prerequisite for durability and nature can be significantly more tolerant to change than expected. It also is equally common sense that change and adaptation have always been a part of the natural environment.
1.2.3 Drift Nets
A particularly irresponsible form of fishing is by means of drift-nets, which hover in the sea as invisible and for many marine species practically undetectable curtains only moved by wind and currents. These "curtains of death" indiscriminately catch everything crossing their path, be it turtles, marine mammals like seals, sea lions, whales and dolphins or sharks, sea birds and many other victimized non-target species ending up as unwanted bycatch. Despite a ban of drift-nets exceeding 2.5 km in length there still are nets of lengths with up to 50 Kilometres continuously drifting in the oceans of seas of the world. But not only net types like drift nets or gill nets are an enormous threat because of their tendency to produce large amounts of bycatch. Another significant problem is long-line fishery, applying lines with lengths of several kilometres and equipped with thousands of hooks with lures. Although this in general is a highly selective catching method, many other animals go after the lures and therefore are caught, including sea turtles, sharks, marine mammals and marine birds - especially Albatross. In fact Albatross are now altogether endangered by long-line fisheries. Other disastrous fishing methods are purse seining and drag-netting. Purse seining in the tuna fisheries was the one fishing method that brought the whole bycatch and discard problem to public attention, mainly because the method included targeting dolphins, which were used as an "indicator species" since they often hunt together with tuna.
1.2.4 Ghost Fishing
Another form of "bycatch" in the widest sense of the world is known as "ghost fishing". It can be defined as "...the continued capture and killing of animals by gear that has been lost or abandoned.[v]"Like other side effects of the large scale industrial exploitation of the sea ghost fishing is a relatively recent phenomenon, as in the past the fishing equipment (nets and lines) were made of biodegradable materials (rope and twine). A classic net that was lost would quickly rot away and/or sink andwhile modern equipment is made of nearly indestructible material such as nylon or other artificial materials. Ghost fishing by lost or discarded equipment include:
--> ongoing killing of target species
--> indiscriminate catching and killing of non-target species
--> damage to and killing of animals by ingesting parts of lost gear
--> potential physical damage to sea floor communities
Since the true extent of ghost fishing is not known, it increases the uncertainty of assessing the overall magnitude of the bycatch problem and hence the overfishing crisis. Within European fisheries one of themost pressing issues in this context are the gillnet fisheries in the North Atlantic which go after monkfish and deep water shark. There are convincing indications suggesting that net dumping occurs on a large scale and hence significant ghost fishing is under way [Open University, 2007]. To get a picture of the dimensions of ghost fishing, it is worthwhile to look at a calculation of Kibel et al (2007), according to which in the order of magnitude of five million crabs are caught in lost pots used as crab traps - in UK waters alone! Around 20% of the trapsare lost annually and here again the use of non-degradable material like stainless steel or plastic instead of traditional material such as woven hazel is one of the main factors. Rotting natural material also tends to be more visible (or otherwise recognizable) than the thin plastic lines of modern gear.
Fishing equipment that was lost or dumped in deep waters with insignificant currents can go on ìfishingî for years to come. In shallow waters with stronger currents and high tidal activity nets and lines tend to get entangled and are therefore are rendered more harmless in a relatively short period of time, perhaps a few months.
1.2.5 Trawling and purse seining
Without any technological adjustment trawling (including prawn/shrimp trawling) and purse seining also result in enormous amounts of unwanted bycatch. Since large scale tuna purse seining was introduced in the 1969s, large numbers of Dolphins have been killed in the process, especially since Dolphins were used as the indicator for the positions of tuna (setting on Dolphins)[vi]. The true numbers of Dolphin deaths are not known, but numbers for Pacific tuna fisheries alone vary between 137,000 for 1986 (Kibel, 2007) and over 200,000 as an upper annual estimate for the 70s (Earle, 1995)[vii].
The blindness of society, practitioners and policy makers alike is well expressed in a quote by Richard Ellis: ìIt is probably no surprise to learn that the massive bycatch of spotters and spinners in the tuna purse-seine fishery has had deleterious effects on dolphin populations; it is only surprising that it took forty years to recognize that killing millions of animals in a population might permanently damage it[viii].î
2. Light at the end of the tunnel
ìOne morning we raised forty to fifty paired Spanish draggers working Green Bank (Grand Bank area)Ö some of them seemed to have a tailÖwhen we came over them at about 2,000 feet, we saw it was dead fish. There must have been millions of them stretching out astern of each boat that had just hauled its net and was sorting the catch on deck. Undersized fish were going over the side like confetti[ix].î
F. Mowat (1984) Sea of Slaughter
2.1 Coping with a Syndrome
Although the situation is dire and many fish stocks and other marine species are close to collapse, or in decline, there also are positive developments giving reason for optimism. Like all environmental issues at the interface of man and nature, the problem of overfishing and bycatch is multi-factorial - a syndrome. An effective approach has to be a combination of solutions on all levels: technological, economical, ethical and political. Every else is prone to fail. The good news is that this development appears to be under way. Some technological and behavioural advances for bycatch reduction are lined out below, sorted by fishing method:
2.1.1 Dolphin safe-tuna the first big success resulting from public pressure
We Humans tend to make a strict distinction between animals we eat and those we love, adore and sometimes keep as pets at least in Western societies. Dolphins for a long time had a positive image, partly reaching back to times of antiquity, partly resulting from popular products of the entertainment industry such as films and TV series (e.g. Flipper) or ìcircus showsî in marine parks. It also is relatively easy to identify with marine mammals since they are highly developed and intelligent mammalians just as we like to see ourselves. Hence once the wider public became aware of the dolphin casualties involved in Tuna fisheries, a large public outcry was the result in many western countries. NGOs utilized the righteous emotional outrage and the call for ìdolphin save tunaî. As it happens the success came fast and Dolphin bycatch in tuna purse seining was reduced from as many as perhaps 200,000 annually to negligible levels to date. The pressure was purely based upon economic incentives: Fishermen were given Dolphin quotas which they could not exceed, and therefore killing dolphins simply would be an expensive enterprise.
One method to avoid killing Dolphins in this form of fishery is the so called ìBackdown procedureî where divers are utilized to release the Dolphins by simply lowering the net to open escape routes. Other technological adjustments such as rescue platforms also were added to the catching routine[x].
At the same tome the unfortunate Tuna despite being magnificent creatures never had such a positive image and may well be hunted to near extinction.
2.1.2 Long Lining some approaches for improvements
Often there is not one single technological answer to a single technological question, and solving the bycatch issue in long-line fisheries is such a case. However, there are a number of promising developments that in combination may well reduce bycatch to tolerable levels at least in terms of commerce and population biology. Such approaches include (See Kibel, 2007):
--> Circle hooks (reducing turtle and sea bird bycatch significantly)
--> Pingers (as deterrents for marine mammals)
--> Applying weights to lures to quickly lower lines beyond levels where they can be reached by birds, or use heavier frozen baits)
--> Deep setting (also adding significant weights to the line to create a deep bow out of reach of birds
--> Automatic release bait pods (a new high-tech approach using a closed bait pod that opens via pressure control at a pre-set depth)
2.1.3 Trawling and excluder devices
One of the few effective technological measures that reduce bycatch in trawling has been the introduction of exclusion devices in the nets. Those basically are rigid grids or similar structures that separate any big animals from the main catch and divert them to a special exit of the net while the main catch is directed to the cod end by the water stream. There are a variety of exclude devices and respective net designs of varying effectiveness, however, their effectiveness all in all must be considered as ìbetter than nothingî, especially since the problem of catch and discard of juvenile specimens of other species remains unresolved. This issue will most likely be addressed, since there again are commercial incentives at play because many of the destroyed juvenile animals would be commercially relevant when larger. Some further improvements of trawling methods are required. The current methods can be broadly categorized into[xi]
--> those that separate species by differences in behaviour
--> those that mechanically exclude unwanted organisms according toothier size (see above).
Excluder devices also do not guarantee that the excluded animals actually are safe they may well be dead or heavily injured from the impact on the device, which would make the damage invisible, but not undone. Among the work that still needs to be done are:
--> Thorough Quantification of bycatches and accumulation of fishery-related information
--> Long-term examination and re-evaluation of modifications
--> Assessment of damage inflicted on escaping(excluded individuals
--> Promotion of recommended designs or regulations/legal and economic incentives enforcing their application
3 The role of ethics
We live in the so called media age, and yet even I an environmental professional, a conservationist, a person who even studied (physical) marine sciences, until very recently did not know the order of magnitude of the bycatch issue. As a well educated thinking individual I often feel bad enough about belonging to a species that sees animals as a part of a farming industry, treating creatures very closely related to us as mere commodities. Realizing that we in fact simply throw away huge numbers of animals and destroy their habitats for purely economic reasons personally makes me less than proud about our great species which I have long re-named from Homo Sapiens Sapiens to Homo Sapiens Potentialis. Sometimes only occasionally there is a glimpse of wisdom and ingenuity among the members of my species. But that certainly is not the hallmark of our race. A nuclear bomb is a clever device, but it is at least debateable whether its actual development and deployment can be seen as a sign of intelligence let alone wisdom. The same is true for our general attitude towards resources and our fellow co-habitants on this planet. I fail to see how we can justify 90% discard only to obtain shrimps. We can live without shrimps.
Often it is said that emotions and philosophy should be kept out of political, economic and scientific discussions. This statement is illogic, as it in itself already is an ethical decision. It inherently puts one set of values above another in that ultimately commercial interests are to be valued higher than anything else. The problem with this view is that economy is not a religion but only a tool, that money is not a value nor an end in itself, but, again, only a means. At the same time there are ancient values and so called common sense that I think are part of what we call culture and civilization. Care. Respect. Caution and yes precaution. The precautionary principle is applied throughout all of our life. Caution and precaution are everywhere. They are part of the human makeup and in fact even the behaviour of higher animals. In situations of uncertainty, we check and verify and choose to not act if the available information is insufficient. We teach our children to look to the left and right before crossing a road; we tell them not to eat unknown berries and not to touch the unknown dog. We bring umbrellas when the sky is grey because it just might rain. We lock our doors and the government affords police systems and ridiculously expensive armies. Out of precaution. The industry especially banks invest enormous effort in risk analysis and management systems. And even within the very limited scope of these artificial man-made systems they tend to fail more often than not. Why then is it that despite the fact that the precautionary principle is a deeply rooted part of our culture, it has been routinely ridiculed over and over again with respect to environmental management on all scales? We now know far too much to go on with such a nonsensical game. And anyone who still needs more facts must be told that precisely our lack of knowledge, our uncertainty, calls for action. Because if the involved complexities and uncertainties especially in the environmental sciences, science is not always the best policy adviser. Scientific controversies are prone to be exploited by diverting political groups and used for their own ends.
ìThere has developed an increasingly intelligent discourse on the subject of the role of science in marine policy and decision making (Ö). This literature attempts to explain how scientific research is used by decision makers in the formulation of marine policies. Essentially, this material has evolved out of the realization that decision making is ultimately a political imperative, with the consequence that policies do not always reflect the findings of scientific research[xii].î
Science does not tell us what to do. Science does not say that wiping out a species is either good or bad. That is an ethical question outside of scientia or knowledge. And there are limits. We must decide for our societies where these limits are. Obviously we do not consider accepting child prostitution on the grounds that it might be a good business. That would be outrageous. We also did not accept mass slaughtering of Dolphins as part of Tuna fishing. But where are the limits? Should it be up to public opinion based upon the cuddle factor of a given animal whether its species will be brought to extinction or allowed to survive? We can talk in sober scientific language about bycatch and destroyed specimens, like US militaries talk about ìcollateral damageî. Or we may see it like Sylvia Earle, who more closely identifies with the marine critters she knows so well:
ìLittle is being done to change Laws that permit agonizing death by suffocation, strangulation, crushing, drowning, panic, shock, slicing, spearing, or other methods of modern fishing. No one doubts that dolphins, whales, seals and birds feel the burn of rough webbing on exquisitely sensitive skin, the slashing bite of knives and gaffs, the searing shock of separation from close-knit societiesÖand no one should doubt that fish do as well[xiii].î
False Killer Whale Pseudorca Crassidens (Own work)
We loose our sense of being without ethical corner stones supporting us and guiding our actions. Maximizing profit cannot be an ethical end in itself that justifies every form of suffering and destruction, especially when even a Portuguese and hence an EU sardine fisherman only earns about 3000 Euro per year it must be asked in all earnestness: Qui Bono?
[i] Thiesen, S.: Orcawelt, a novel, Norderstedt Verlag, Hamburg (as yet unpublished, translated from German)
[ii] Lighthouse Foundation, http://www.lighthouse-foundation.org, 2007
[iii] S.C. Clarke et al, Ecology Letters, 09/2006
[iv] Currie, D and Parry, G.: Effects of scallop dredging on a soft sediment community: a large-scale experimental study, Mar Ecol Prog Ser, Vol. 134, 1996
[v] Life in the Oceans - Exploring our blue planet, Open University, 2007
[vi] Kibel, P.: Exploitation and Conservation of Marine Resources, University of Exeter, 2007
[vii] Earle, S.: Sea Change A Message of the Oceans, Fawcet Columbine, 1995
[viii] Ellis, R.: A Sea of Blood, Mare, June/July 2006
[ix] This is a quote from a pilot in the Royal Canadian Airforce who flew over the Grand Banks region in the northern Atlantic in the 1950s. Taken from: Life in the Oceans - Exploring our blue planet, Open University, 2007
[x] Kibel, P.: Exploitation and Conservation of Marine Resources, University of Exeter, 2007
[xi] Broadhurst, M.: Modifying Dredges to Reduce By-catch and Impacts on the Benthos, in By-catch Reduction in the Worldís Fisheries, Springer, 2007
[xii] Bache, S. and Evans, N.: Dolphin, albatross and commercial fishing: Australiaís response to an unpalatable mix, Marine Policy, Vol. 23, Elsevier, 1999
[xiii] Earle, S.: Sea Change A Message of the Oceans, Fawcet Columbine, 1995
Submitters Website: http://thiesen.webnode.com/
Stefan Thiesen is a Germany, UK and USA educated earth and space scientist and science writer. He is an expert in marine science, climatology and planetary sciences, author of several popular science books in German and English as well as a novel and numerous short pieces. During the last years his professional work focused on solar energy and solar energy based water desalination and treatment solutions with projects in Europe, Africa and Asia. One of his Water Projects was a finalist in the World Bank Development Marketplace Competition of 2006. Since summer 2006 Stefan works for the development dept. of a leading European solar energy company.
Other fields of interest include marine protected areas and traditional land and ocean management. He was invited speaker on international conferences, including EU and NATO advanced research workshops. Stefan lives on an ancient farm in Westfalia/Germany together with his wife Yvette, three daughters Sophie Maris (meaning "Wisdom of the Sea"), Liv Moana (meaning "Sea Life") and Stella Marina (Meaning Star of the Sea) as well as their dog Amie.