Bluefin Fishing by Sport Fishermen Off the Trebeurden Bay, Northern Brittany, During the 1946-1953 Period

SCRS/2008/059 Collect. Vol. Sci. Pap. ICCAT, 63: 69-78 (2009)

BLUEFIN FISHING BY SPORT FISHERMEN OFF THE TREBEURDEN BAY, NORTHERN BRITTANY, DURING THE 1946-1953 PERIOD

Alain Fonteneau1 and André Le Person

SUMMARY

This paper describes and analyses the short history of the giant bluefin seasonal sport fishery that took place in the Trebeurden Bay, Brittany, France, after World War 2. This fishery was clearly linked with a now vanished sardine local resource and artisanal fishery, and it was targeting giant bluefin that were probably migrating back from the North Sea and Norway. The history of these sardine and tuna fisheries is discussed in relation with the potential tuna migrations. The end of the bluefin fishery in 1953 was probably related to the local extinction of the sardine stock. This event confirms the great interest to analyse data from bluefin sport fisheries, and the paper recommends doing more data mining targeting the recovery of historical sport fishery data.

RÉSUMÉ

Cet article décrit et analyse la brève histoire de la pêcherie saisonnière de gros thons rouges qui a été active dans la Baie de Trébeurden, en Bretagne, France, après la deuxième guerre mondiale. Cette pêcherie était clairement liée à une ressource locale de sardine, qui était exploitée alors par une pêcherie artisanale. Cette pêche sportive visait de gros thons rouges qui revenaient probablement de la Mer du Nord et/ou de Norvège. L’historique de cette pêche à la sardine et de thons rouges est discuté en relation avec les possibles migrations des thons. La fin de cette pêche sportive en 1953 était probablement due à la disparition du stock local de sardine. Cet épisode montre bien l’intérêt scientifique des pêcheries sportives de thon rouge, et il est recommandé de tenter de réunir un maximum de ces données historiques sur les pêcheries sportives de thon rouge.

RESUMEN

Este documento describe y analiza la breve historia de la pesquería deportiva estacional de atún rojo gigante que se desarrolló en la Bahía de Trébeurden en Bretaña, Francia, tras la Segunda Guerra Mundial. Esta pesquería estaba claramente vinculada a un recurso local de sardina, ahora desparecido, que era explotado entonces por una pesquería artesanal. Esta pesquería deportiva se dirigía a atunes rojos gigantes que probablemente migraban desde el mar del Norte y Noruega. Se discute la historia de estas pesquerías de sardina y atún rojo en relación con las potenciales migraciones de los túnidos. El fin de la pesquería de atún rojo en 1953 se debe probablemente a la desaparición del stock local de sardina. Este hecho confirma el interés científico en analizar los datos de las pesquerías deportivas de atún rojo, y este documento recomienda intentar reunir el máximo posible de datos históricos sobre las pesquerías deportivas de atún rojo.

KEYWORDS

Bluefin, sport fishery, history, Brittany, feeding migration

1. Introduction

The goal of this paper is to describe and to analyse the history and the fate of a small sport fishery developed in Northern Brittany, France that was targeting large bluefin during the 1947-1953 period in the Trebeurden Bay2. The history and bluefin catches of this seasonal sport fishery has never been described in the scientific literature,

1 Fonteneau Alain, IRD scientist, CRH, BP 171, Sète, France. E Mail: [email protected] 2 Trebeurden Bay is often called Bay of Lannion, but the first term has been kept because the city of Lannion does not have a direct access to the sea, and because the fishing events described in the papers mainly took place in Trebeurden. 69 but the information still available on this fishery has been collected and it allows to rebuild a comprehensive review of its activities, in relation with the Mediterranean and North Sea bluefin fisheries that were active during this period on the spawning and on the feeding bluefin tunas.

2. Material and methods

The local information on the Trebeurden Bay sardine and sport fisheries used in this paper has been collected locally and from various local sources and local archives. All the data concerning the bluefin North and Mediterranean seas and on the movement patterns of bluefin tuna in the region have been taken from the scientific literature. The main goal of the paper will be to rebuild the history of the Trebeurden Bay bluefin sport fishery between its birth in 1947 and its end in 1953, and to put this history in relation with the local sardine fishery that was then active in the same area. The potential relationship between these tunas and those fished seasonally in the Mediterranean Sea and North seas will be discussed later.

3. A summary and overview of bluefin tuna migrations during the 1940s and 1950s

Bluefin migratory routes in the Northern Atlantic during the 1940s and 1950s are well documented and described by scientists (among others by Mather 1995, Farrugio 1981, Fromentin and Powers 2005, Tangen 2008), primarily based on the seasonality of the fisheries and on the recoveries of tagged bluefin. In summary, there is no doubt that during this period there was each year a massive seasonal migration pattern between its spawning strata in the Mediterranean Sea (in June) and its North Sea feeding zones (July to September) (Figure 1). Such migration took place at least during most of the 20th century, but it later vanished during the seventies, probably in relation with the lack of herring, not to a collapse of the bluefin stock. However the exact trajectories of these north-south migrations have not been fully identified. The relative importance of a British Channel migration route versus a Faeroe Island route north of Scotland has not been estimated, keeping in mind that while bluefin tunas have seldom been noticed by scientists in the British Channel, the frequent catches of giant bluefin taken as a by-catch off Boulogne sur Mer (MacKensie 2007, Figure 10) would tend to indicate that the British Channel could also be a migration route for bluefin.

4. A post war WWII seasonal sardine fishery off Brittany

It can be noticed from historical records that their was during the end of the 19th century and the first half of the 20th century a small scale traditional fishery targeting sardines off the Trebeurden Bay, in northern Brittany (Figure 2). This fishery was mainly based in the port of Locquemeau, but also in Trebeurden. A dozen of boats were fishing sardine in 1870 in the Trebeurden bay, and 70 vessels in 1880. These fishing vessels were either simply using oars (Figure 4) or they were sailing boats with two masts and a small crew, typically called « flambart ». Sardines were fished each year from May (some years since March) to October (or November some years). This fishery was exploiting small sardine during summer time, a yearly recruitment being targeted by the fishery in August (juvenile sardines in a size range between 4 and 5 cm). The fishery was using a straight drift net, about 50 meters long and at a depth of only 3 to 4 meters. Sardines were attracted towards the drifting nets by cod eggs, or « rogue » imported from Norway, and sardines schools were simply « netted »: a good catch being 300 kg of sardine in a set/day. Total yearly catches of this artisanal fishery have been estimated and they were at a low level under 300 tons yearly (Figure 3). It was noticed by fishermen that the major difficulty in this fishery was the local abundance of three enemies: sharks, porpoise and “unknown large fishes”, as these top predators produced an irreversible escapement of sardines and also serious damages to the nets. From fishermen testimonies (Yves Allain), it was noted that porpoise and the “unknown large fishes” had different feeding behaviours: porpoises were often entangled in the net, and destroying it, while predatory fishes were feeding on sardines already entangled or not, but without being entangled in the net. This small local stock of sardines vanished during the mid fifties, probably due to environmental causes: the last sardines were caught and sold in the Trebeurden streets in 1956 (and they never came back).

5. 1946-1953: 8 years of giant bluefin seasonal sport fishery in the Trebeurden Bay

5.1 Birth of the bluefin fishery in Trebeurden

The history of the bluefin Trebeurden fishery starts during the ssummer of 1946, the first full summer after World War 2, when the first bluefin was caught off Trebeurden. During this summer, sardine fishermen made

70 various complaints upon the fact that very large and unknown fishes were steeling large amounts of sardines caught in their nets. At this time, none of these very large fishes had been caught by any fisherman and the species involved was still unknown. Dr. Miroux was a doctor working in Lannion and he had good contacts with various sardine fishermen. He was curious to catch one of these very large predatory fishes, at least to identify them. In order to reach this goal, Dr. Miroux build an ad hoc fishing/hunting gun made with a Mauser gun, a harpoon and a rope used by mountaineers, and in October 1946 he went to sea with sardine fishermen. It was a successful fishing trip by Dr. Miroux and a first fish was quickly harpooned: it was a 2,50m bluefin weighting 175 kg (Figure 5). This catch was a proof and a surprise for everybody, including the fishermen, that large bluefin tunas were present in the Trebeurden Bay predating on sardines. Surprisingly these large bluefin were still entirely cryptic and had never been identified before by fishermen (for instance never jumping out of the water).

Dr Miroux was a good sport fisherman, but he did not had any experience in tuna fishing, so he made contact with various sport fishermen experienced in bluefin sport fishing. These contacts will lead to the next fishing season, the first one in terms of sport fishery, when in August 1947 a team of experienced US sport fishermen, Michael and Helen Lerner, came to Trebeurden (Figure 6). They came to Trebeurden from the USA on an ocean liner with a full staff of assistants, bringing their wide experience, and a lot of sophisticated fishing gears and their outboard engines that were still missing in Brittany after World War 2. In the absence of any sport fishing boat, they used and equipped local fishing boats, used with minor technical adjustments (Figure 7). These fishing vessels were the traditional wooden fishing boats from northern Brittany, specially equipped with an outboard engine imported from the USA, and equipped with a home made fishing chair placed in the bow of the boat (Figure 7). The bluefin fishing spots were located in shallow waters, at very short distances from the coast, and very close to the 2 fishing ports of Trebeurden and Locquemeau, allowing a quick and easy access to the tuna grounds by these rather slow fishing vessels. This sport fishery was following all the international IGFA rules as the Lerner family and Ritz team were fully experienced in this fishing mode. The search for bluefin tuna was permanently conducted in full cooperation with the local sport and sardine fishermen, and there was a visual signal shown by sardine fishermen when a bluefin tuna was identified close to their drifting nets.

5.2 Seasonality and variability of the bluefin fishery, and sizes taken

Large bluefin tunas were targeted and caught each year in the Trebeurden Bay during the 1947-1953 period, but there was a significant variability in the yearly catches taken by sport fishermen: some years were quite poor, such as 1948 due to bad weather, while other years such as 1949 were excellent (1949 was also excellent in the Copenhagen sport fishery in Denmark).

The marked seasonality of this bluefin fishery should also be noticed, as the bluefin fishing season was quite short and peculiar, in general between August 25 and September 15, and with some additional weeks before and after during some years.

Sizes caught by the sport fishery have often been noted in newpapers and in the records of the Trebeurden tuna club. Some of these sizes were obtained and computerized, and the size distribution of these sampled fishes is shown in figure 8b. The estimated average weight of this sample is close to 175 kg, bluefin caught in Trebeurden being in a range between 76 and 322 kg (keeping note that this larger bluefin was not caught following the IGFA rules). This range of size corresponds to a quite wide range of ages between approximately 8 and 15 years (and a mode at about 10 years). Similar sizes of large bluefin were caught during the 8 year period.

These bluefin sizes taken in the Trebeurden Bay were similar to bluefin caught by purse seiners during the same period in the North Sea (Figure 8a). Smaller sizes of the Trebeurden bluefin can be noticed, but it is possibly/probably due to the difficulties to catch the larger bluefin using the quite historical equipment used in Brittany during the 1947-1953 period: rod and reel and fishing vessels.

5.3 Origin of the Trebeurden Bay bluefin?

As adult bluefin tunas were caught in the Trebeurden bay at sizes similar to the typical Norwegian bluefin during the same period, it can easily be hypothesized that these tunas were probably taken in the Trebeurden Bay during their backward migration from the North Sea. These bluefin were feeding on sardines (preferably juveniles) during their stop over trip in Brittany, after feeding predominantly on (juvenile) herrings in the North Sea (Hamre). This Trebeurden hot spot was probably linked to the bluefin memory to remember an interesting known feeding zone and also to fidelity for this feeding spot. This fidelity was probably acquired by a given 71 micro-cohort (or a given group) of bluefin. Such localized “feeding spot memory” is seldom envisaged for tunas but for bluefin tuna it may constitute a realistic and strong hypothesis (similar trophic fidelity being well demonstrated for southern bluefin tagged by archival tags, Gunn and Young 2000). Such a memory also implies an efficient navigational ability to come back to a peculiar coastal feeding hot spot, but such navigational efficiency has been often demonstrated for tunas by the results of multiple archival tags on a wide range of species (Sibert and Nielsen 2001). Furthermore, it can also be noticed that bluefin tunas were also described as being common in the sardine fishery of the Douarnenez Bay, at the Western edge of Brittany, an area with a long history of active sardine fisheries; however this presence of bluefin off Douarnenez remains hypothetical, as they were never caught by any sardine or sport fishermen

It is not clear if these schools of bluefin moving back home from the North Sea were going to the Central Atlantic and/or Mediterranean Sea or/and the Western Atlantic: both hypotheses could be realistic, as large percentages of these 2 sub-populations where identified (from tagging and from Norwegian fishermen’s testimonies) feeding in the North Sea during these years.

5.4 1953, the end of the Trebeurden bay bluefin fishery

The last bluefin was caught in the Trebeurden Bay on the 14th of September in 1953: a 197 kg bluefin caught in Trebeurden Bay by a British sport fisherman, Mr Clifford Stubbings, on board the Loquemeau fishing vessel Caot Glas and its then famous captain Mr Efflam Coadalen. The same year 1953 was also the end of the sardine fishery in the area: when the sardines vanished from the Trebeurden area, the bluefin did not come back to the area. The end of the sardine fishery in the area is probably due to environmental factors and to the great “natural” variability of small coastal pelagic stocks. However, local sardine fishermen also had the hypothesis idea that sardine schools were widely attracted in the Trebeurden by the Norwegian cod eggs, the “rogue”, and that the end of the local fishing activities reduced the local feeding concentrations of sardines. At least this is for scientists a new and interesting hypothesis. On the other hand, it should also be kept in mind that great quantities of large bluefin were still taken in Norway and in the North Sea until the mid-1960s (Figure 9), while these tunas never came back to feed in the Trebeurden Bay after 1953 and the collapse of the local sardine stock.

6. Conclusion

This now vanished sport fishery provides to scientists a typical and good example of the rather unique but typical flexibility of bluefin feeding zones and of their strange and highly variable migration patterns. It is also a confirmation that giant bluefin may remain cryptic and unnoticed by sardine fishermen during many years. Similar cryptic biomass of giant bluefin was also frequently indirectly reported by fishermen’s testimonies in another major sardine fishery from Brittany, in the Bay of Douarnenez, but if these bluefin were sometimes indirectly reported by sardine fishermen, they were never caught by sardine fishermen. This Trebeurden event also gives a confirmation that sport fishermen can provide very useful information to scientists. Such an event should lead to a recommendation that ICCAT should promote an active data mining targeting the recovery of data on bluefin sport fisheries data, for instance and at least since the beginning of the 20th century. This data mining should for instance target the various sport fisheries targeting giant bluefin since the beginning of the 20th century on the East coast of the United States, in England, in Denmark and possibly also in Norway and Sweden. This event also probably provides a confirmation that the British Channel was also used by bluefin, at least in some of its migration back from North Sea. It also provides a clear confirmation that bluefin feeding concentrations and local fisheries can be driven by the great local variability of small pelagic resources, independently of bluefin stock biomass. As a consequence, such local CPUE of feeding bluefin should never be used in assessment models as being indicators of stock biomass at an Atlantic wide level. This event also supports the hypothesis of the bluefin capabilities to repeat, during several years, their newly discovered feeding routes that are targeting very small feeding hot spots. It can also be concluded, in terms of sport fisheries, that such local historical event would have been widely different today in relation with the present potential huge fishing effort exerted by sport fisheries: the biological event observed in the Trebeurden Bay during the 1950s, would probably produce today much larger bluefin catches, due to the large number and great fishing efficiency of modern international sport fishermen.

References

Farrugio, H., 1981. Exploitation et dynamique des populations de thon rouge, Thunnus thynnus Linné. (1758) atlanto-méditerranéennes, Thèse Doctorat d’Etat, Univ. du Languedoc, 325p.

Fromentin, J.-M., Powers, J.E. 2005. Atlantic bluefin tuna: population dynamics, ecology, fisheries and management. Fish and Fisheries 6:281. Gunn, J., Young, J. 2000. Environmental determinants of the movements and migration of juvenile southern bluefin tuna. In Hancock, Smith and Koen Eds, Fish movements and migration, pp123-128

Hamre, J., 1958. Tuna investigations in Norwegian coastal waters 1954–1958. Ann. Biol. (ICES) 15, 197–211.

Mackenzie, B.R., Myers, R.A. 2007. The development of the northern European fishery for north Atlantic bluefin tuna Thunnus thynnus during 1900-1950

Mather, F.J., Mason, J.M., Jones, A.C. 1995. Historical document: life history and fisheries of Atlantic bluefin tuna. NOAA Technical Memorandum, NMFS-SEFSC-370, No. 370. NOAA NMFS.

Sibert, J., Nielsen, J.L. 2001. Electronic tagging and tracking in marine fisheries. Edited by Sibert J. and J.L Nielsen. Kluwer Academic Press, 468p.

Tangen, M. 2008 Norwegian fishery on Atlantic bluefin tunas 1920-1985. Conference given at this Symposium, a summary from the book by the same author: “Storjefisket pa vestlandet”, EIDE edit., 163p.

Boulogne Trebeurden

Figure 1. Map showing typical pattern of bluefin seasonal migrations in the eastern Atlantic (taken from Tangen 2006).

Trebeurden

Locquemeau

Figure 2. Location of the Trebeurden bay in Northern Brittany, France (Google map).

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1945 1946 1947 1948 1949 1950 1951 1952 1953 Figure 3.Yearly sardine catches in Trebeurden Bay during the 1945-1953 period.

Figure 4. Trebeurden Bay, early 50ies, a typical artisanal fishing vessel bringing on board its sardine catches entangled in its driftnet (baited with cod eggs).

Figure 5. October 1946, Trebeurden harbour, the first bluefin caught by Dr Miroux, using a Moser gun and a harpoon (bluefin caught: 2,50m and 175 kg) (collection Docteur Michel Miroux).

Figure 6. September 4, 1947, Doctor Miroux (left) and Michael Lerner (right) landing a couple of bluefin in the Trebeurden fishing port. (collection Docteur Michel Miroux).

Figure 7. Bluefin sport fishery off Trebeurden in 1947: a traditional sardine boat transformed into a sport fishing vessel (collection Docteur Michel Miroux).

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Figure 8. Typical sizes of bluefin caught by the purse seine North Sea purse seine fisheries (left) and by the Trebeurden Bay sport fishery (sample of recorded catches) during the 1946-1953 period.

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Figure 9. Yearly catches of bluefin, taken by the North Sea fisheries, predominantly at large sizes. The period during which bluefin were caught in the Trebeurden Bay is also shown.

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Figure 10. Yearly by-catches of bluefin taken at the entrance of the British Channel by the herring fishery from Boulogne (data from French Affaires Maritimes, taken from MacKenzie 2007).