This article originally appeared in The Shark Tagger-1997 Annual Summary
In 1997, members of the Cooperative Shark Tagging Program (CSTP) tagged 8,816 fish representing 31 species of sharks and rays and 11 species of teleosts (Table 1). This is the second highest number tagged in a single year (second only to 1996) and brings the total to more than 147,000. Sharks and teleosts were tagged primarily by recreational anglers (68%) fishing with rod and reel and tagging free swimming sharks, and by NMFS and other biologists (21%) using longlines, gill nets, and handlines. An additional 1,016 fish (11%) were tagged by commercial fishermen and fisheries observers on board commercial vessels. United States fishermen, in conjunction with taggers from England, Canada, Portugal, Ireland, France, and Spain were responsible for the tagging effort.
The principal shark species tagged were blue (68%), sandbar (9%), tiger (4%), mako (3%), Atlantic sharpnose, blacktip, and porbeagle (each 2%). Sport fishermen tagged the vast majority of blue sharks, making this the second highest number of blue sharks tagged in the history of the CSTP. In addition, NMFS and other biologists tagged more than 400 blue sharks on research cruises in 1997. The number of sandbar sharks tagged has also been increasing in recent years, largely due to the cooperative efforts of NMFS biologists and other researchers and fisheries observers investigating inshore shark-pupping areas. Nearly 50% of the sandbar sharks tagged in 1997 were neonates (newborns) in Delaware Bay (this research is described in more detail in the Field Studies section of the Newsletter).
In addition to the standard "M" type dart tag that most taggers are familiar with, NMFS biologists are also using a yellow plastic-tipped dart tag and a blue plastic rototag. These latter two tags are used exclusively on small sharks. The blue rototag is a small fin tag applied through the first dorsal fin of the shark. Please watch out for these new tags and report information on tag number, species, sex, measured fork length, location, date, and capture gear. If you are sacrificing the animal, please also take a piece of the backbone for ageing studies. These data are critical to studies of coastal shark nursery grounds.
In 1997, information was received on 685 recaptured fish representing 21 species of sharks and 4 species of teleosts. Blue (482), sandbar (61), tiger (34), porbeagle (23), and mako (22) sharks represented the predominant species recaptured (Table 2). This was another record year in terms of recaptures, and brings the total to nearly 7,500 fish. The recaptured fish were originally tagged by recreational anglers (73%), NMFS and other biologists (15%), and commercial fishermen and fisheries observers onboard commercial vessels (12%). In contrast, tagged fish were recaught primarily by anglers (52%) and commercial fishermen and fisheries observers (47%). Recapture information was obtained from fishermen representing 14 countries: U.S. (459), Spain (125), Canada (44), Japan (20), Mexico (9), Portugal (9), Venezuela (8), Cuba (3), Dominican Republic (2), France (2), Italy (10), Bermuda (10), Uruguay (1), and Ireland (1). In addition to the enthusiastic and valuable support from U.S. anglers and commercial fishermen, continued cooperation with fishermen and biologists from countries across the Atlantic has made 1997 another successful year for the CSTP and shark research.
Times at liberty ranged from 1 day to 7.1 years - The majority of the blue shark recaptures (275) were at liberty for less than 1 year; 153 at liberty from 1 to 5 years; and 5 were at liberty for greater than 5 years. Two of these recaptures were the sixth and eighth longest times at liberty to date (6.1 and 7.1 years). Overall, 173 of the blue sharks were released after initial capture, 107 with and 66 without a tag. Of these retags, eleven were caught again. Short-term multiple recaptures (6), which were tagged and recaptured in the summer off Rhode Island and New York over a 2.5 month period in 1997, demonstrated fine scale movements of the individual fish in a localized area.
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A multiple blue shark return from a previous year's tagging was tagged in October of 1996 and first recaptured in July of 1997, only 55 nm away. It was recaptured again 16 days later, 3 nm away. Although this longer term multiple recapture may show little overall migration, its actual movements during the initial 9 months at liberty are unknown. In contrast, another long-term multiple recapture was tagged and recaptured after one year within 17 nm of its original tagging location off Rhode Island; then retagged and resumed another year later, 2,134 nm away off the Azores. The use of archival tags on this pelagic species will help unravel the mysteries of these movements by providing a more comprehensive picture of the migration timing, routes, and cues that may trigger these migrations (see "Archival Tag Experiment").
Distances traveled ranged from 1 to 3,374 nm - Overall, 225 blue sharks traveled distances less than 100 nm; 82 between 100-500 nm; 24 between 500-1,000 nm; and 112 greater than 1,000 nm. Of these, 23 traveled over 2,000 nm and 2 over 3,000 nm (third and tenth longest distance recorded in the CSTP). The shark that traveled 3,374 nm was tagged southeast of Montauk Pt., NY and recaptured just north of the equator (east of Brazil) after 1.8 years. One traveling 3,129 nm had been tagged off Sable Island, Canada and recaptured off Sierra Leone after 3.7 years at liberty. Other long distance recapture locations included the Flemish Cap, Azores, Portugal, Canary Islands, Cape Verde Islands, Western Sahara, Surinam, Guyana, Venezuela, Dominican Republic, and Cuba.
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The number of long distance returns (> 1000 nm) in 1997 is more than double the number reported in 1996, and is a result of the extraordinary cooperation from international biologists and fishermen. Information on a total of 174 blue shark returns was received from people from Spain (113), Canada (21) Japan (16), Portugal (9), Venezuela (7), Cuba (3), Dominican Republic(2), Italy(1), Bermuda (1) and Ireland (1). These data are critical to begin to fully understand the complex migrations of this highly migratory shark species.
Interesting returns - Six blue sharks, tagged by NMFS, Narragansett Laboratory biologists east of Massachusetts in September of 1996, were returned in 1997. These sharks were all recaptured after less than one year (0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 years) at liberty and from 110 to 2,041 nm away. The areas of return were spread across the Atlantic with the furthest recapture returned after the shortest amount of time. These points of recapture include the waters off the Canary Islands, Azores, Flemish Cap, Nova Scotia, southern Massachusetts, and New York. The latter two recaptures were during the summer months when blue sharks are commonly found in the New York Bight area.
Another group of 14 blue shark returns were all tagged by R/V Geronimo biologists within one week of each other off Martha's Vineyard, MA in late June and early July of 1996, and recaptured after approximately one year. Distances traveled ranged from 46 to 2,546 nm and points of return were scattered from the northeastern U.S. (Maryland, New York, New Jersey, and Maine) to Newfoundland, the Flemish Cap, Azores, and Cape Verde Islands.
Other interesting long distance returns included: two blue sharks tagged almost one year apart (June of 1995 and 1996) off Long Island, NY that were recaptured in the same place off Guyana; a blue shark tagged northeast of Antigua and recaptured 1,039 nm in mid-ocean after eight months at liberty; a blue shark tagged in the English Channel and recaptured southwest of the Azores (1,710 nm; 0.8 years); and a group of eight blue sharks, tagged by recreational fishermen off Spain and Portugal, that were recaptured after up to 2.2 years at liberty and distances of 1,108 nm.
Times at liberty ranged from 2 days to 13.4 years - Thirty sandbar sharks were recaptured after less than 1 year; 23 at liberty from 1 -10 years, and 3 were returns from 10-15 years. The longest time at liberty for any tagged sandbar shark returned in 1997 was 13.4 years. This fish was tagged by a recreational fisherman in August of 1983, off Long Island, NY and was recovered by a fisheries observer off North Carolina. With the exception of four fish, all short-term recaptures (< 1 year) were neonates.
Distances traveled ranged from less than 1 to 1,938 nm - Most (40) of the sandbar sharks were recaptured less than 300 nm from their original tagging location, however, 3 traveled more than 1000 nm. These three fish were all recaptured in the Gulf of Mexico; one off Florida and two off Texas after traveling from the waters off New Jersey, New York and Massachusetts. Three other sandbar sharks, tagged in the Atlantic, were recovered in the Gulf of Mexico off southwest Florida. All local returns (distances traveled of < 25 nm), in 1997, were neonates with the exception of four fish; three were tagged off Florida and recaptured after one, two, and three years at liberty; and the fourth was at liberty for 6.5 years. These local returns, recaptured during the same time of year as tagging, suggest that some sandbar sharks may retum to the same general location in subsequent years.
Interesting returns - As part of an ongoing shark nursery grounds study (see Sandbar Shark Nursery Study and Length at Birth of the Sandbar Shark in Delaware Bay), 392 neonate sandbar sharks were released with tags in Delaware Bay in 1997, of which 20 were recaptured. Seventeen were recaptured inside the Bay with times at liberty ranging from 2 to 62 days and distances traveled from 1 to 13 r m. These local returns were all tagged in the months of July (nine) and August (eight) and recaptured as late as the end of September in the Bay. One neonate was recaptured with no information on location. The other two sandbar sharks, which were tagged in Delaware Bay, were recaptured as they migrated south to their over-wintering grounds. One was returned off Chincoteague Inlet, VA in October (77 days; 56 nm) and the other off Folly Inlet, NC (91 days; 333 nary).
Eight sandbar sharks tagged in previous years as neonates were recaptured in 1997. Four of these fish were tagged on their pupping grounds (two in Great Bay, NJ and two in Delaware Bay). The two New Jersey fish were tagged at the same time and place in 1996 and were recaptured together 9 months later after traveling 260 nm. Of the two Delaware Bay fish, one was tagged in 1995 and recaptured off Georgia after 1.8 years at liberty; the other was tagged in 1996 and recovered in Delaware Bay, only 21 nm from its original tagging location after 1 year at liberty.
Four other neonates were recaptured. These fish were tagged by a biologist in October of 1996 off North Carolina after having presumably migrated south from their northern summer pupping grounds. After 8-9 months at liberty, three of these fish were recovered in Chesapeake Bay, VA, another primary sandbar shark nursery area. The other neonate was returned from the same area of tagging in March of 1997.
These and other neonate recaptures will help us delineate migratory patterns, and the location of primary pupping, nursery and over-wintering areas. In addition, they may answer questions on site fidelity, whether neonates return to their pupping grounds, and for how many years.
Times at liberty ranged from 1 day to 2.2 years - Fifteen tiger sharks were recaptured less than one year after tagging; eight were at liberty from 1 to 2 years; and 1 fish was at liberty for more than 2 years. Ten tags were returnedwith no date information, precluding the calculation of time at liberty.
Distances traveled ranged from less than 7 to 2,373 nm - The majority (31) of the tiger sharks made coastwide migrations from 100 to 300 nm, traveling farther north in the warmer months. There were two exceptions in 1997, which have followed a pattern observed in recent years. One tiger shark was first tagged in September of 1995 and recaught and re-released with the same tag one day later and 8 nm away. The fish was recaptured again 2.2 years later after traveling 2,373 nm to an area 800 nm west of the Cape Verde Islands. The other shark was tagged off North Carolina in January of 1996 and recaptured 1.5 years later approximately 600 nm south of the Flemish Cap (a distance 1,549 nm). These are the fourth and tenth longest distance traveled to date for any tiger shark previously tagged in the CSTP. Both of these fish were tagged by biologists and positively identified as tiger sharks at tagging. These sharks are only the fourth and fifth out of 620 that have shown long-distance movements to an area south of the Flemish Cap or transatlantic migrations toward the African coast.
Interesting returns - In addition to the multiple return just discussed, another tiger shark was recaptured twice. This fish was originally tagged off Georgia in January of 1997 and first recovered off North Carolina after 6 months at liberty and traveling 266 nm to the northeast. He was re-released with the same tag, recaptured two days later (28 nm away) and released again with the tag in place. At each point of tag and recapture, the tiger shark was caught and measured by the same biologist. Repeated returns of this kind show that juvenile sharks can survive the catch and release process and provide information on growth and fine scale migration routes.
Another interesting return was a tiger shark that was tagged southwest of Puerto Rico and recaptured south of Anguilla Island in the Lesser Antilles (1 year; 284 nm). Recoveries from unusual tagging locations are critical to help elucidate the migrations of such wide ranging coastal-pelagic shark species as the tiger shark.
Times at liberty ranged from 6 days to 9.2
years - The 9.2 year return was the longest time at liberty for any porbeagle
tagged in the CSTP (prior record was 8.6 years). This shark was tagged east of
Martha's Vineyard, MA by a fisheries observer, in 1987, and was recaptured by a
Canadian commercial fisherman east of Cape Sable, Nova Scotia, Canada after
traveling a distance of 268 nm northeast. Overall, 5 sharks were at liberty
less than 1 year, 5 from 1 to 2 years, 5 from 2 to 3 years, 7 at liberty from 4
to 5 years, and 1 at liberty greater than 5 years.
Distances traveled ranged from 20 to 426 nm - All porbeagle recaptures in 1997 were returns from sharks tagged in the western Atlantic with the exception of two fish. Both of these sharks were tagged and recaptured in the English Channel after up to 1.5 years at liberty and traveling distances up to 67 nm. There have been less than five porbeagles returned from this area in the records of the CSTP.
Interesting returns - Three porbeagles were recaptured in the Gulf of St. Lawrence. Two were originally tagged in the Gulf of Maine and one on Sable Island Bank. All were at liberty from 2.8 to 3.7 years and traveled distances from 243 to 391 nm. Up to this time, only two other porbeagles, tagged by members of the CSTP, have been recaptured from this area. Other returns this year showed similar patterns of localized movements between U.S. and Canadian waters (see 1996 Shark Tagger).
Times at liberty ranged from 13 days to 12.8 years - The 12.8 year recapture is the longest time at liberty for any mako recorded in the CSTP. The previous record was 9.5 years. This shark was originally tagged from the research vessel R/V Geronimo in 1984 off Oregon Inlet, NC and was recaptured off South Carolina by a fisheries observer on a commercial longline vessel. In addition, a piece of the backbone was collected to verify current age estimates. This recapture proves that shortfin mako sharks live at least 13 years; this longevity information is critical to the management of this valuable resource. Two other returns were at liberty for more than four years (4.9 and 5.2 years). These are the seventh and ninth longest times at liberty on record.
Distances traveled ranged from 19 to 1,142 nm - Five mako sharks in the 1997 data show distances/raveled of less than 100 nm; 10 between 100 and 500 nm; and five traveled greater than 500 nm. Data on these long distance recaptures were supplied by foreign fishermen. Information on two sharks was returned by a Spanish biologist; both makos were recaptured southwest of the Azores and traveled over 700 nm from their original tagging location, one after three months and one after 3.8 years at liberty. Two other fish, which were originally tagged off the northeast coast of the U.S. and recaptured southwest of the Flemish Cap by Japanese longline fishermen, traveled distances greater than 1,000 nm. The fifth long distance mako shark return was a southern hemisphere tag and recapture; tagged off Argentina and resumed off Brazil (853 nm; 4.9 years). This is only the second mako return that was both tagged and recaptured in the South Atlantic. Overall in 1997, information on ten shortfin makos was received from cooperating foreign biologists and fishermen from Canada, Spain, Japan and Uruguay.
Interesting returns - One fish, tagged south of Montauk Point, NY, was recaptured on Jeffrey's Ledge off Rockport, ME (149 nm) after 5.2 years. There are less than five shortfin mako shark returns that show movement into the Gulf of Maine.
Recaptures of other species included some long distance and maximum time at liberty records for the CSTP. A great hammerhead shark that was tagged of the west coast of Florida, was recaptured off Campeche, Mexico (637 nm; 2.6 years). This is only the fourth great hammerhead recaptured to date, the first recovered from Mexican waters, and is a record time at liberty and distance traveled for this species. A spinner shark traveled 148 nm from Port Everglades, FL into the Gulf of Mexico after 4.4 years at liberty. This is the longest time at liberty for this species. Other interesting recoveries include: an Atlantic sharpnose shark that traveled from Chincoteague Inlet, VA to Folly Inlet, NC (272 nm; 6.9 years) (second longest time at liberty and sixth longest distance); a scalloped hammerhead at liberty for 7.9 years (fourth longest time at liberty); a longfin mako at liberty for 5.5 years that traveled 1,852 nm from Tobago Island to offshore of Cape May, NJ (record time at liberty and distance traveled); and a blacknose shark that traveled from the Florida east coast to Georgia after 2.2 years. This is only the ninth blacknose shark recaptured to date, the third longest at liberty, and the fifth furthest distance.