Vol. 6 (1): June 2003

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The location of the Cabo Blanco peninsula monk seal colony in a desert environment might make one believe that the colony has always been safe from human disturbance and persecution. The reality is quite different, however. Two nearby cities and an increasing population on the peninsula has meant that human activity has also been on the rise, and is today one of the main pressures affecting the colony. Its foreseeable increase in the future is likely to make human disturbance one of the greatest threats to the seals in recent times.

Goose barnacle pickers descending from cliff-tops on the ‘Coast of Seals’.

Following the discovery and commercial exploitation of the large West African “sea wolf” herds in the 15th century, the Cabo Blanco monk seal colony remained relatively undisturbed from land until the 20th century. During that century, the foundation and subsequent growth of the nearby cities of La Güera and Nouadhibou (ancient Port-Etienne), both closer than 30 km to the monk seal colony, led inevitably to an increase of human pressures upon it...

Disturbance to the animals increased over the years, while at the same time people became more aware of the seals’ presence nearby. Western inhabitants of both La Güera and Nouadhibou even acquired the habit of spending the weekend visiting the “Coast of the Seals” and, as a matter of fact, that place eventually became marked by a big stone monolith signposting the exact location of the animals.

When Eugenio Morales Agacino first described the Cabo Blanco colony in 1945, he already noted that the Spanish military posted at La Güera (at that time this area was still part of the Spanish Sahara) knew about the colony because of its “hunting trips”.

Subsequently, in the 1970s, Maigret, Duguy and Trotignon became alarmed about the effects of human disturbance upon the seal’s breeding and resting habitat. In referring to the seal’s dwindling numbers and dispersion, they wrote that, “certainly, this last factor [human disturbance] has played the primary role, either disturbances caused by excessive visitors, or by the bullet shots to the seals”.

In 1975, Ramón Soriguer visited the coasts of the Spanish Sahara in order to verify rumours of a mass mortality among the seals at the Cabo Blanco colony. Rather than finding evidence of a sudden die-off, however, Soriguer attributed the body count at Cabo Blanco to a progressive decrease in the seal population. Thanks to the pictures he took then, we can identify even today the exact place where he saw his seals. It is a cave allowing easy access, where curious visitors could reach even the inner beach without too much difficulty. He penned some sentences that reflect the human pressure that the colony was suffering at that time. The author writes: “The cave is continuously disturbed by tourists and shellfish collectors from nearby Nouadhibou. These visits, which frighten away seals, take place practically every weekend.” He also warns of another source of disturbance, reporting that, “according to our news, in the last two years at least six young seals have been collected from the colony” – a reference to live captures.

	Inner beach of the Soriguer cave, which in 1975 was occupied by seals.

Of these various forms of disturbance, visits by the curious had a significant impact upon the colony between 1950 and 1975, when the Sahara war began. It is difficult to know what really happened on this coast during the war years. What is certain is that, as far as the sea is concerned, war brought a paradoxically more peaceful environment for the seals, making the fishing boats that had combed the area up until then, quickly disappear. In contrast, consequences brought about by the conflict on land for the breeding and hauling-out areas of the seal are far more uncertain. After the end of the war, the presence of land mines in the area notably limited the presence of curious onlookers and tourists, but with basic human needs as the driving force in a poor country, they did not deter goose barnacle pickers for very long.

The fact that, in 1975, Ramón Soriguer already made reference to these men – whom he referred to as “shellfish harvesters” – made us wonder about the intensity and impact of such disturbances, which still persist to this day.

Shellfish pickers descend from the cliff-tops to harvest goose barnacles in the intertidal area, and although they don’t interact negatively with seals – neither attacking nor showing any hostility towards them – they do cause disturbance in the locations occupied by the animals and possibly also deter the seals from re-colonising historically-occupied habitats.

When the first expedition of the Spanish team arrived on this coast in 1992, the presence of shellfish fishermen was already established. As a matter of fact, one of them assisted the team to minimize the dangers of the mine fields.

In 2001, the Fundación CBD-Habitat team mapped the entire coastline in the vicinity of the breeding caves, recording not only types of geomorphologic formations (cliffs, beaches, beaches with cliffs, caves with sea entrances, accessible caves, rock falls, cave collapses, etc) but also traces of shellfish collector activity (like discarded shell accumulations, rope and ladder fixation points, ropes and ladders abandoned, etc).

A CBD-Habitat technician among an accumulation of discarded shell fragments on the Coast of Seals.

Along this entire stretch of coastline, intense goose barnacle exploitation was detected. Practically 100% of beaches protected by cliffs, as well as accessible caves, rock falls, and rock entrances where there existed a possibility of harvesting goose barnacles, bore signs at the cliff-top of collector activity. Only over caves with marine entrances, completely inaccessible to shellfish pickers (such as breeding caves 1 and 3, today occupied by seals), were there no signs of activity.

In an excursion to the interior of the Soriguer cave, we found what appeared to be remnants of a discarded net. Closer observation, however, revealed that this was actually a sack tightly secured to a rock inside an intertidal pool. There was no doubt that this was a place used by shellfish fishermen to store goose barnacles and keep them wet and alive until they could be transported to the city (today they perform this same activity in a rocky area south of the protected zone controlled by the CBD-Habitat surveillance patrol). Monk seals do not actually occupy this cave at present, although apparently it is identical in condition to when visited by Soriguer in 1975. Undoubtedly, disturbance by tourists and fishermen might have caused the animals to abandon it.

When interviewed, two of the most experienced shellfish harvesters on the Coast of the Seals both indicated that this kind of activity was habitual before 1975 and originated at a time when the territory was still a Spanish colony (very believable due to the Spanish love of this shellfish). Unwittingly, they confirmed Soriguer’s observations.

From the city of Nouadhibou (now with over 100,000 inhabitants) shellfish fishermen regularly arrive at the Coast of the Seals, where CBD-Habitat has been performing continuous patrols since 2000. The proximity of the city, its great expansion in recent years and the strong basic needs of its inhabitants, has led to intensifying human pressures on the monk seal colony, often manifesting itself in waves of goose barnacle fishermen [see Prestige disaster has consequences for Cabo Blanco, this issue].

Land surveillance is currently of fundamental importance, if there is to be any hope of maintaining tranquillity essential to the viability of the breeding colony and to the conservation of the species on the Coast of Seals.

References

Monod, T. 1923. Note sur la présence du Monachus albiventer Bodd. Sur la côte Saharienne. Bull. Mus. Nat. Hist. Nat. Paris 29, 555-557.

Morales-Agacino, E. 1945. Las focas del Sahara. Calendario mensual de caza y pesca 26: 45-46.

Maigret, J., J. Trotignon and R. Duguy. 1976. Le phoque moine (Monachus monachus) sur les côtes meridionales du Sahara. Mammalia 39: 413-422.

Soriguer, R.C. 1976. Problemática y medidas de conservación de la foca fraile (Monachus monachus) en el Sahara Occidental. Doñana Acta vertebrata 3: 75-78.

Copyright © 2003 Pablo Fernández de Larrinoa, Miguel Ángel Cedenilla, The Monachus Guardian. All Rights Reserved