The transportation of live silky sharks (Carcharhinus falciformis) on standard palletized aircraft cargo positions for long distance and time period transports. Forrest A. Young, Director Dynasty Marine Associates, Inc., David C. Powell, Curator, Emeritus, Monterey Bay Aquarium, Richard Lerner, Curator of Fishes, Ocean Journey, Denver CO. January 1, 2000.
The silky shark, Carcharhinus falciformis, is a species that has only recently been displayed in public aquariums, and to date, little information has been compiled on its behaviour and husbandry requirements. As far as the authors are aware, this species has only been collected and displayed by Steve Kaiser, Dave Wert and Glenn Kelly at Atlantis Resorts, Paradise Island, Bahamas, Jerry Crow at Sealife Park, Hawaii and Kiyonori Nishida at the Osaka Aquarium Kaiyukan. Atlantis' and Sealife Park's proximity to the open sea obviously minimizes the transportation difficulties that most aquariums face in acquisition and acclimation of display animals. The transport to Osaka was by sea and truck and was relatively short in its time period. Nonetheless, the work done at the three institutions with pelagic sharks has been quite impressive.
The silky shark is quite similar to the blacknose shark, C. acronotus' capability to survive brief capture stress and brief transportation times to the quarantine system. In total, about 60 to 90 minutes represents the maximum time from capture (by rod and reel) to introduction into a 7m by 20m by 1.5m holding tank where mostly all animals that are captured, will survive. The author suspects that longline capture is even more stressful as it greatly increases the "in water stress" time period. Once the silky shark is acclimated to captivity it seems to be a hardy and visually impressive husbandry candidate.
Until the present time, they have not ever been transported over any significant distance or transported in an aircraft (David C. Powell, pers. com). It was the hypothesis of the authors, that the methods that we have developed at Dynasty Marine Associates, Inc., that considers the basic spatial and dynamic requirements of similar species such as C. acronotus and the more challenging blacktip shark, C. limbatus, would also work for C. falciformis.
This approach was developed during experimentation that was initiated in the desire to provide captive specimens of small pelagic sharks, especially Carcharhinus limbatus, C. acronotus and bonnethead shark, Sphyrna tiburo, and the scalloped hammerhead, Sphyrna lewini to public aquariums. Small Caribbean carcharhinids, specifically C. limbatus are extremely sensitive, obligate ram-ventilators and are difficult to collect and transport. On board the collecting vessel, maintenance of totally pelagic, obligate ram- ventilators requires highly specialized methods and holding containers.
All totally pelagic shark species have a great degree of difficulty recognizing and negotiating barriers in their swim path and the resultant stress levels caused by repeated container contact is an etreme major obstacle to their adaptation to immediate captivity. The energy budget required to negotiate these tight turns in rectangular boxes very quickly depletes the energy reserves of the shark, especially when the animal is already arriving on board the boat in a highly stressed condition from being caught on a baited hook, fought on the tackle and landed at the boat. The staff at Dynasty Marine Associates has for some time been developing and modifying a large, round holding tank system (hammer paper in press) that takes into account the initial difficulties for these species. The primary obstacle is that the size of the container is limited to the size and carrying capacity of the boat.
The results that have been achieved bear out the merit of the hypothesis. Collections of two 1m C. falciformis were made on two separate collecting trips and they were acclimated in the holding system for about three weeks. During this time, the sharks were fed daily and ate ravenously on squid and cut mackerel at about 2% of total body weight/ day.
Once the sharks were adequately acclimated, food was withheld for four days and the authors shipped them via truck to Orlando and from there by cargo aircraft to Denver. The transport containers that were previously developed for transporting hammerheads were used (hammer paper in press) and one 1m shark was shipped in each of two 2.5 m diameter containers. Total transportation time from holding tank to aquarium was about 26 hours. Both sharks swam in the containers during the entire trip and ate the day after the transport.
One shark developed a slightly cloudy eye, presumably from contact with the transport container in route. An oral Baytril regimen was administered and this cleared up the injured eye within 10 days. Slight rostral damages, also presumably from perhaps either capture injury and or container contact were also observed and these healed completely within 30 days from the time of transport. This is not unusual in small pelagic carcharhinids or sphyrnids.
The ideal temperature for the species seems to be above 25 C. and below 28 C. There were several low pressure weather systems that occurred during the holding and acclimation period and the resultant cool water in the semi-open system with temperatures below 23 significantly slowed swimming speeds and overall activity levels. Feeding was also sporadic below 23 C. and did not occur much at all below 21 C. The senior author has since observed feeding in C. falciformis twice in about ten observations at about 20 degrees C. It is interesting to also note that the senior author has noted several mortalities in C. acronotus below 18 and 19 C. that for lack of any other factor that could be found have been attributable to the cold temperatures. In the sea, these species are never found in water below about 22 or 23 degrees C.
The short term conclusions indicate that medium length transports of durations of 24 to 36 hours present slight risk of mortality the principal risk is of equipment failure, transport mishandling by the airlines or flight cancellations. It is also the authors' conclusions that transport durations up to as much as 48 hours are possible with only slightly elevated risk. Also, the transport of two sharks per container is quite likely to represent a miniumal risk on shorter duration transports of 24 hours or so transports.
The senior author recently supervised a 38 hour transport of two, one meter sized C. acronotus with no mortalities, a thirty hour transport of three C. acronotus, where one mortaility was observed out of six animals transported and up to six, 50cm to 60cm C. limbatus, for transports up to 56 hours with a high degree of success. The risk of stress and mortaility is always minimized if fewer animals are transported in the same container and is always recommended.
It is the authors' conclusion that many other species of small and medium size, totally pelagic sharks can be collected and transported by these methods and that their husbandry will be researched in detail during the next few years. Up until this time, very few species of visually impressive sharks were available for aquariums to display. These have been primarily the brown shark, Carcharhinus plumbeus and the sand tiger shark, Odontaspis taurus. With the increase of availability and interest in other new and sometimes smaller, pelagic species, new displays are sure to follow, especially those that more easily accomodate the requirements of the smaller species.