On the Ocean Sunfishes (Mola mola, Linnaeus 1758) By-Caught Off the Mediterranean Coast of the Gaza Strip, Palestine

The Ocean Sunfish or Common Sunfish or Common Mola
(Mola mola, Linnaeus 1758) belongs to the Molidae family...


1758); Slender Sunfish (Ranzania laevis, Pennant 1776); Sharptailed Sunfish (Masturus lanceolatus, Liénard 1840) and Short
Sunfish (Mola ramsayi, Giglioli 1883) in addition to two other Mola species A and C waiting formal scientific naming [3]. Despite its worldwide occurrence in temperate and tropical seas [4], the Ocean Sunfish is well known to scientific parties and fishermen of most Mediterranean countries as the heaviest and largest bony fish worldwide [5]. It can grow up to a length of 2.7 m and weigh 2.3 tons [2,6]. It has a body which is flattened laterally. The most obvious physical characteristic of the fish is the replacement of its caudal fin by a broad, stiff lobe called the pseudocaudal fin or clavus which plays as a rudder. Sims et al. [7,8] pointed out that despite the lack of caudal propulsion of the Ocean Sunfish; it remains a powerful swimmer capable of highly directional horizontal movements, deep-water dives and even breaching.
In this bizarre morphology (Figure 1), the fish resembles a half fish thus, having the description of a swimming head [9]. The fish is also characterized by its powerful dorsal and anal fins that seem to be the primary means of locomotion. The slow locomotion rhythm of the Ocean Sunfish makes it subject to large predators, such as large sharks, orcas (Killer Whales) and sea lions [10,11]. The fish may dive below the thermocline to avoid predators [12]. It is well known for the Ocean Sunfish to spend up considerable time of the day basking in the sun near the surface of the water; a behavior aiming at re-warming their bodies up after deep water dives to hunt [12][13][14]. Another hypothesis for sun basking behavior of the fish is ectoparasite elimination as pointed out by Abe, et al. [15] and Abe et al. [16,17]. Although the wide-ranging Ocean Sunfish is a generalist predator in the sense that it consumes a broad food items including small fishes, squids and other mollusks, zooplankton, crustaceans and brittle stars, it is well known as an obligate gelativore, feeding on dangerous jellyfishes (phylum Cnidaria or Coelentrata) prevailing at marine ecosystems and causing harm to swimmers and people [18][19][20][21][22][23].
The jellyfish food item may lead them to ingest plastic debris accidentally. The Ocean Sunfish is not a commercially important fish although there is some market for it in some Asian countries [24]. From a conservation point of view, the Ocean Sunfish is subject to extremely high level of incidental by-catch in the global fisheries including the Mediterranean fisheries [12,25,26]. The Ocean Sunfish and other Mola species were recorded in the marine waters around the world including the Mediterranean Sea, Red Sea and Middle East countries [10,25,[27][28][29][30][31][32][33][34][35][36][37][38]. Although the Gaza Strip (365 km2) is a small piece of land lying at the southwestern coast of Palestine on the Mediterranean Sea, its 42-km beaches experienced from time to time discarded or stranded specimens of the Ocean Sunfish, having various sizes. The key aim of this paper is to provide information on Ocean Sunfishes (Mola mola) caught off the Mediterranean coast of the Gaza Strip, Palestine. In fact, the fish is rarely seen in the Palestinian marine waters because of its solitary and erratic habits in spite of the fact that it is the most frequently encountered Mola species worldwide [39]. The importance of the current study comes from the fact that it is the first study dealing with the Ocean Sunfish in Palestine.

The Gaza Strip
The Gaza Strip (31°25′N, 34°20′E) is an arid to semi-arid strip of the Palestinian land along the southeastern Mediterranean ( Figure   2), having an area of 365 km2, and a population of about 2.0 million, of whom the majority are United Nations-registered refugees. The Gaza Strip is one of the most densely populated places in the world [40]. It has a total number of about 3,500 fishermen working on about 1,000 fishing vessels of different sizes and capacities [41].

The Marine Ecology of the Gaza Strip
Since the Introduction of the Palestinian National Authority to Palestine (West Bank and Gaza Strip) in 1994, more focus was paid by the environmental bodies to the marine ecosystem of the Gaza Strip, which was totally neglected during the era of Israeli Occupation. Studies on the marine ecology of the Gaza Strip, in spite of their rarity, were carried out in an atmosphere characterized by a total absence of specialists in such marine disciplines and a total presence of anthropogenic stresses facing the marine environment and fishery resources. As a result, marine fauna was rarely surveyed or studied by the Palestinian scientific parties [40,41,43,44]. In the last couple of years, works on marine fishes were carried out and gave considerable data. More recently, Abu Amra [45] conducted a modest study and surveyed as many as 128 bony fish species occurring in the marine ecosystem of the Gaza Strip, of which the Ocean Sunfish was the largest fish species encountered.
Shaheen [46] carried out a study dealing with pisciculture

Occurrence and Local Accidental Catch of Ocean Sunfish
Knowledge on the occurrence of the Ocean Sunfish at the Mediterranean coast of the Gaza Strip is increasingly growing scientifically and in the field. Abd Rabou et al. [43], Abd Rabou [44] and Abu Amra [45] ensured the occurrence of the species among the ichthyofauna of the Gaza Strip. A good fraction of Gazan fishermen was found to be aware of the Ocean Sunfish and its ecological role in the marine environment (Personal Communications). Although the Slender Sunfish (Ranzania laevis) and the Short Sunfish (Mola ramsayi) were recorded at the Kuwait and Omani waters [27,32], they have never been recorded among the Mediterranean fishes of the Gaza Strip [45]. At least, 20 specimens of the species were known to be separately caught off the Mediterranean coast of the Gaza Strip by drift gill nets since 2006, i.e. during the last 15 years.
The heaviest specimen was recorded in December 12, 2006 ( Figure   3). The on-site discussion with local people including fishermen revealed that the fish was so heavy to the extent that 20 men tried to pull it out from the water, but they failed [49,50]. At the global level, Sunfishes are accidentally but frequently caught in drift gillnet fisheries, making up nearly 30% of the total catch of the swordfish fishery employing drift gillnets in California. Most of specimens were caught during the cooler months of the year extending from November to April (Figure 4). This could be attributed to the accidental by-catch of the fish during its upward movement in order to exert sun basking as a behavior trying to elevate its internal temperature after diving in cold deep waters [51]. According to Fulling et al. [52], Ocean Sunfishes were sighted with greatest frequency during the winter (December -April) in sea surface temperature < 24° C. They attributed such sightings in winter to the basking behavior which is commonly associated with thermoregulation in addition to the oxygen replenishment after long, deep dives to oxygen-deficient depths. Sun basking could be related to ectoparasite elimination as well [15]. Figure 4 illustrates some of the discarded Ocean Sunfishes caught off the Mediterranean coast of the Gaza Strip. Ocean Sunfish [27,30,32,38] (Table 1).

Morphometric Characters Approximate Measurements (cm)
Total length (measured horizontally from the tip of the mouth to the end of the cla¬vus) 280 The distance between the tips of dorsal and anal fins 285

Distance between bases of dorsal and anal fins 173
Height of dorsal fin 132

Height of anal fin 140
Pre-dorsal fin length 162 Pre-anal fin length 148 Body depth (measured vertically at the widest points of the body margin) 196

Local Consumption of Ocean Sunfish
Ocean Sunfishes are considered a delicacy in some parts of the world such as Japan, Korea, and Taiwan. They are used in traditional Chinese medicine as well [24]. In the European Union, regulations have been issued to ban the sale of fish and fishery products derived In a study carried out in Spain, 47.2% of 106 sunfish examined were found to host Accacoelium contortum [54]. The ectoparasites and endoparasites of the fish motivate it to seek relief in a number of ways. The breaching behavior of the Ocean Sunfish and the intense cleaning efforts of various marine organisms markedly reduced the initially severe ectoparasite loads including the attached copepods and trematodes [55]. Barreiros,et al. [56] encountered the Goose Barnacle (Lepas anatifera), which is a Cirriped belonging to phylum Arthropoda, attaching to the esophagus of the Ocean Sunfish. Such association may cause feeding problems since the attachment of this Cirriped may obstruct the fish's esophagus. Such parasites may cause diseases to Ocean Sunfishes and end their lives ( Figure 5).

Local Threats Facing Ocean Sunfishes
The fishery by-catch, and destruction of the Ocean Sunfish are unregulated events worldwide. It is well supposed that the fishery by-catch, and discards are increasing with increase of fishing efforts and enhanced production as well [25,52]. The population of the species is considered as Vulnerable (VU) in IUCN Red Lists category [57]. In the marine ecosystem of the Gaza Strip, the threats imposed on the species seem to coincide with those prevailing around the world. The Ocean Sunfish are likely being hit by boats and being caught as by-catch in fishing gear used by Gazan fishermen. The floating litter; particularly plastic bags which resemble jellyfish, a common prey item of Ocean Sunfishes, forms another threat in the marine environment. The sources of such solid waste items were known to come from the Palestinian fishery fleet, local beach establishments like resorts and shops, and raw or semi-treated wastewater discharged in big quantities into the Mediterranean coast [41].
In this regard, Wadi Gaza is one of the main wastewater discharging points into the Mediterranean along the coast of the Gaza Strip [58]. Nylon bags can choke and suffocate the Ocean Sunfish and other marine biota like sea turtles or fill their stomach to the extent that they starve [59]. Although the process in not