The Story of a Swordfish Andrew Sammut. It is intended that this presentation…. gives an overview...
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Transcript of The Story of a Swordfish Andrew Sammut. It is intended that this presentation…. gives an overview...
““It is intended that this It is intended that this presentation…. gives an presentation…. gives an overview of the life of…. overview of the life of…. AA SWORDFISHSWORDFISH….. from ….. from
when it is born till it when it is born till it reaches adulthood reaches adulthood
and….later on finds itself and….later on finds itself on….on….
…………. Andrew’s . Andrew’s plate for lunch”plate for lunch”
Dad meets mum- SpawningDad meets mum- Spawning
Best spawning grounds are found Best spawning grounds are found in the Mediterranean Seain the Mediterranean Sea
Adults spawn in all months except Adults spawn in all months except January and FebruaryJanuary and February
Spawning is most intensive from Spawning is most intensive from end of June to Augustend of June to August
Mum swordfish lays 2 to 5 million Mum swordfish lays 2 to 5 million eggseggs
The Swordfish is BornThe Swordfish is Born……
Eggs are fertilized Eggs are fertilized externally and float at externally and float at the sea surface due to the sea surface due to
the presence of a droplet the presence of a droplet of oil of oil
They hatch after 2.5 days They hatch after 2.5 days
Babies (fry) up to 5 kg Babies (fry) up to 5 kg have been recorded from have been recorded from
October to DecemberOctober to December
Large numbers of babies Large numbers of babies are found from are found from
November to MarchNovember to March
Characteristics of Swordfish FryCharacteristics of Swordfish Fry
Swordfish fry - recently hatched fish Swordfish fry - recently hatched fish larvae - are different from adultslarvae - are different from adults
Upper & lower jaws are equally Upper & lower jaws are equally prolongedprolonged
Bodies are long, thin and snakelike Bodies are long, thin and snakelike They are covered with rough, spiny They are covered with rough, spiny
scales and plates scales and plates Tails are rounded Tails are rounded Have just one long dorsal and anal finHave just one long dorsal and anal fin
Growth RateGrowth Rate Swordfish grow extremely fast during their first Swordfish grow extremely fast during their first
year of life and may reach 90cm by one year of age year of life and may reach 90cm by one year of age
After two years of age, females tend to grow faster After two years of age, females tend to grow faster and to a larger size than malesand to a larger size than males
Females are heavier than males at the same lengthFemales are heavier than males at the same length
Maximum size: 4.5m in length and 540 kg in weight Maximum size: 4.5m in length and 540 kg in weight
Reaches reproductive maturity at about 5 to 6 Reaches reproductive maturity at about 5 to 6 years of age, when about 2m in lengthyears of age, when about 2m in length
Characteristics of an Adult Swordfish Characteristics of an Adult Swordfish (Xiphias gladius)(Xiphias gladius)
Known asKnown as Piscispat or Pixxi spad in Piscispat or Pixxi spad in MalteseMaltese
Lose all teeth and scales by adulthoodLose all teeth and scales by adulthood
The Sharp BillThe Sharp Bill
The swordfish is The swordfish is named after its named after its sharp bill which sharp bill which resembles a swordresembles a sword
Sharp bill is used to Sharp bill is used to injure prey injure prey
Defensive against Defensive against natural predatorsnatural predators
Cold bloodedCold blooded
Have special Have special organs near eyes organs near eyes and brain which and brain which improves heatingimproves heating
This helps in their This helps in their vision and catch vision and catch their prey easilytheir prey easily
Not Schooling FishNot Schooling Fish
Swim alone or……Swim alone or……
…….. in loose aggregation having a .. in loose aggregation having a swordfish 10 meters apart from the swordfish 10 meters apart from the otherother
Very powerful and vigorous when harpooned Very powerful and vigorous when harpooned or hookedor hooked
Known to have run their bill like a sword Known to have run their bill like a sword through planking of small boatsthrough planking of small boats
Known for their powerful Known for their powerful jumping on surface called jumping on surface called
breachingbreaching
Enjoys swimming at surface of Enjoys swimming at surface of water airing their dorsal finwater airing their dorsal fin
TheThe Favorite Food for the Favorite Food for the SwordfishSwordfish
Pelagic fish such as flying fish, Pelagic fish such as flying fish, barracuda and small tunabarracuda and small tuna
Fish in Benthic zoneFish in Benthic zone
The squidThe squid
Pelagic fish on which the Pelagic fish on which the swordfish feedsswordfish feeds
The Pelagic ZoneThe Pelagic Zone
Open ocean zoneOpen ocean zone Part of water located Part of water located
in open waterin open water Part of water not Part of water not
near coastnear coast Different zones Different zones
characterized by characterized by their depththeir depth
Swordfish feeds on fish found in Swordfish feeds on fish found in the Benthic Zonethe Benthic Zone
Ecological region at Ecological region at lowest part of the lowest part of the waterwater
Enjoys eating SquidEnjoys eating Squid
Enemies of the SwordfishEnemies of the Swordfish
Very few natural predators in adulthood Very few natural predators in adulthood but highly vulnerable when youngbut highly vulnerable when young
Short fin mako shark is one of few sea Short fin mako shark is one of few sea creatures which are big and fast enough creatures which are big and fast enough to kill a swordfishto kill a swordfish
Other enemies are sperm and killer whaleOther enemies are sperm and killer whale
Short fin mako sharkShort fin mako shark
But the greatest threat to But the greatest threat to swordfish is HUMANS!!!!!swordfish is HUMANS!!!!!
FisheriesFisheries
Caught in gill nets with harpoon & on Caught in gill nets with harpoon & on longlines (see slide further on re: local longlines (see slide further on re: local visit to Fort San Lucjan)visit to Fort San Lucjan)
By CatchBy Catch
Long linersLong liners Consists of a Consists of a
main line, main line, usually usually several miles several miles long, which long, which is supported is supported in the water in the water column by column by floats and floats and from which from which baited hooks baited hooks are are suspendedsuspended
In addition, swordfish are often In addition, swordfish are often an incidental catch in the tuna an incidental catch in the tuna
fishery known as by catchfishery known as by catch
This is used on allThis is used on all
non-target fish whether non-target fish whether retained and sold or retained and sold or discarded (Hall, 1996) discarded (Hall, 1996)
The swordfish is cut into The swordfish is cut into piecespieces
Swordfish & Mercury IntakeSwordfish & Mercury Intake
While swordfish sold on commercial While swordfish sold on commercial markets is closely monitored to make markets is closely monitored to make sure that methyl mercury levels sure that methyl mercury levels remain below the 1.0 ppm action remain below the 1.0 ppm action level, most experts urge those level, most experts urge those concerned about chemical concerned about chemical contaminants to take certain contaminants to take certain precautionsprecautions
Practical tips to avoid Practical tips to avoid mercury consumptionmercury consumption
Avoid eating excessive amounts of any single type Avoid eating excessive amounts of any single type of fishof fish
Avoid eating the internal organs of the fish—they Avoid eating the internal organs of the fish—they
typically contain higher contaminant concentrations typically contain higher contaminant concentrations than the fleshthan the flesh
High-risk individuals — pregnant women, women of High-risk individuals — pregnant women, women of
childbearing age, and children under age 15 — childbearing age, and children under age 15 — should limit their consumption of swordfishshould limit their consumption of swordfish
Use cooking methods like baking or broiling to Use cooking methods like baking or broiling to allow fats and juices to drain awayallow fats and juices to drain away
Andrew and Mark (scientific Andrew and Mark (scientific officer at San Lucjan)officer at San Lucjan)
A comparison in size between Tuna Fish A comparison in size between Tuna Fish (above) and Swordfish (below)(above) and Swordfish (below)
The Flying Fish - the favorite The Flying Fish - the favorite food of the Swordfishfood of the Swordfish
Additional InformationAdditional Information
Ernest Hemmingway (1899-1961), one of Ernest Hemmingway (1899-1961), one of America’s best writers and winner of Nobel America’s best writers and winner of Nobel Prize for Literature (1954) spent long years Prize for Literature (1954) spent long years in Cuba. in Cuba.
One of his pleasures of life was fishing for One of his pleasures of life was fishing for swordfish.swordfish.
This is reflected in his novel, This is reflected in his novel, The Old Man The Old Man and the Seaand the Sea, which was published in 1952., which was published in 1952.
Later the novel was adopted for a famous Later the novel was adopted for a famous film, in which actor Spencer Tracey stared.film, in which actor Spencer Tracey stared.
The Swordfish CatchThe Swordfish Catch
Ernest Hemming in Ernest Hemming in Cuba with his friend Cuba with his friend Mike Lerner and Mike Lerner and their swordfish their swordfish catch (from catch (from Hemmingway in Hemmingway in CubaCuba by H. by H. Hemmingway and Hemmingway and C. Brennan, C. Brennan, Ruggedland, 2005)Ruggedland, 2005)
World Record SwordfishWorld Record Swordfish
382 kg382 kg Caught in 1936Caught in 1936 In ChileIn Chile