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FAQs about strandings

What is a stranding?
NOAA’s National Marine Fisheries Services (NMFS) defines a stranded animal as any dead marine mammal on shore, any live dolphin or whale cast ashore or unable to return to its natural habitat, or any live seal that cannot leave shore due to injury or poor health.

A single stranding occurs when one dolphin, whale, porpoise, or seal comes ashore by itself dead or alive and in need of intervention.  A mass stranding is an event where two or more dolphins or whales (other than a mother/calf pair) strand at the same time in close proximity to one another.  (Seals and baleen whales do not mass strand.)  Mass strandings sometimes involve over 100 individual animals. On Cape Cod, we have frequent single and mass strandings, averaging 226 stranded animals per year.

What types of marine mammals are stranding on Cape Cod?
Four species of seals and fifteen species of cetaceans (dolphins, whales and porpoises) have stranded on Cape Cod’s shores since the stranding network began consistently documenting these events in 1998.

Why are there so many mass strandings on Cape Cod?
Cape Cod is one of only a few places in the world where mass strandings (multiple whales, dolphins or porpoises beaching simultaneously) occur on a regular basis.  There are many theories regarding the causes of these strandings throughout the world.  Often, the causes of these large events remain a mystery.  While we may not know definitively what caused a given mass stranding event on Cape Cod, there are several factors that contribute to their occurrence:

  1. Social bonds – Some cetacean species have very strong social bonds.  These cohesive social groups make a lot of sense in the wild because there is safety in numbers.  Animals evade predators and hunt more effectively in a group.  However, these same social bonds can lead to trouble when one individual ventures into tidally influenced coastal waters.  Whether it is a dominant animal, a sick individual, or a very young animal that heads toward shore, the whole group will often follow leading to a mass stranding when the tide falls.
  2. Location, location, location – There are a handful of places on the planet that experience mass strandings on a regular basis.  Cape Cod usually ranks among the top three sites each year for the frequency of events.  Many of these sites share similar traits with Cape Cod, including a hook-shaped land mass jutting out into the water, gently sloping beaches and convoluted estuarine systems.  All of these factors can contribute to a mass stranding.
  3. Tides – The species that commonly mass strand are pelagic, or offshore animals.  In the Cape Cod region, this includes Atlantic white-sided dolphins, common dolphins, pilot whales, and Risso’s dolphins.  Since these animals spend most of their lives in the deep waters of the open ocean, they are not accustomed to tidal fluctuations.  As a result, when they venture into nearshore coastal waters, they can be caught high and dry when the tide recedes.
  4. Weather – Scientists also theorize that extreme weather may play role in causing some mass strandings and we believe this is true for some of the events that have occurred on Cape Cod.  High winds, coupled with extreme tides may push animals closer to shore, leaving them stranded when the tide falls.



The Marine Mammal Protection Act was first passed in 1972. It mandated the creation of a stranding network of which The Marine Mammal Center is a member.

Who responds to a stranded marine mammal is determined by the location of the animal and who is qualified to address the needs of that species.

Marine mammals strand for a variety of reasons. Strandings may be small-scale events involving single animals, or larger-scale events involving dozens of animals. Strandings may be routine, caused by commonly seen injuries, diseases or malnutrition, or they may be extraordinary, caused by less common circumstances, such as marine mammals found on roadways.

Some marine mammals strand because of harassment or injuries caused by humans, such as entanglement in fishing gear or marine debris, ingestion of plastics, gunshot wounds, or boat strikes. Some strand due to injuries caused by sharks or other natural predators. Many animals strand because of illness or disease, including viral infections such as herpes; bacterial infections such as leptospirosis; parasites; encephalitis; and cancer, to name a few. Still others strand because of natural or anthropogenic (human-caused) toxins in the environment. Sometimes young animals who have become prematurely separated from their mothers or who are recently weaned strand because they have not been successful in finding food. Other times, environmental and oceanographic events such as El Niño cause changes in distribution and abundance of marine mammal prey, thereby leading to malnourishment and stranding.

The causes of stranding are numerous. As sentinels of the marine environment, marine mammals have a great deal to tell us about the health of our oceans. Stranded animals carry that message to us.



Why marine mammals strand

The causes of strandings
Single strandings, strandings of only one animal, can occur for a number of reasons. Dolphins, whales, porpoises, and seals may strand alone when the animal becomes lost or disoriented or is suffering from an illness, infection or injury. Newly weaned animals sometimes have a hard time thriving on their own and may strand as a result of their own inexperience.  Older animals may also die of natural causes.  Unfortunately, our actions as humans can often affect marine mammals.  Some animals strand and/or die as a result of human interaction. The detrimental interactions include entanglement if fishing gear and marine debris, being struck by ships, being shot, and even being harassed by well-meaning beachgoers.  Over the last ten years, almost 7% of the marine mammals stranding in our response region suffered from some form of Human Interaction.

The phenomenon of mass strandings affects only cetaceans (dolphins and whales, infrequently porpoises). Mass strandings occur when two or more of these animals strand (excluding a mom/calf pair) within the same general geographic region and within the same tidal cycle.  There are usually multiple factors that play a role in causing these events.  The one constant thread among all mass strandings is that like humans, the species of whales and dolphins involved are highly social animals that depend upon the safety and resources of the group in order to survive. This group mentality that is so helpful to these animals at sea can unfortunately cause otherwise healthy animals to strand en masse when they are near shore. When one animal enters shallow water or strands, the entire group may follow.

Other factors that may contribute to a mass stranding include predator evasion, complex topography, tidal fluxes, extreme weather, geomagnetic anomalies, and sonar or other acoustic disturbances.  Mass strandings of whales and dolphins have occurred on Cape Cod for hundreds of years, thus it is unlikely that the events in this region are the result of modern human activities.

Social structure:
The species of cetaceans (dolphins and whales) that typically mass strand are often pelagic (offshore) animals that form tight social groups. Unfortunately, the very social bond that serves them so well at sea may be the cause of their downfall as they come close to shore.  These animals stick together at all times, so if one animal becomes sick, injured or disoriented, the entire group may strand instead of just the one affected dolphin or whale.

Scientists and researchers believe that threats by predators such as sharks and orcas may cause marine mammals to swim closer to shore where they are at increased risk of stranding.

Complex topography:
Animals come near shore at different times of the year and may become disoriented and trapped by complex inlets and the hook-like shape of areas such as Cape Cod, Massachusetts.  Wellfleet Bay is an additional hook of land within Cape Cod Bay, and this added level of topographic complexity is likely the reason that 60% of all mass strandings in this area have taken place in Wellfleet.  Researchers have also found similarities in the substrates of areas around the world with a high propensity for mass strandings: these locations tend to have gently sloping sandy or muddy flats that may inhibit the animals’ ability to navigate.

Extreme tidal fluxes:
Mass strandings often coincide with full and new moon tidal cycles. The extreme high and low tides during full moons allow animals to swim farther inshore than normal, leaving them high and dry when the tide turns.  The tides in Wellfleet Harbor can fluctuate up to 12 vertical feet (high tide to low tide) during a full moon cycle.

Extreme weather:
High winds and stormy seas can cause a storm surge, allowing animals to go farther inshore than usual, making them more likely to become stuck when the tide recedes.  It is also thought that these conditions may increase the likelihood that animals become disoriented in complex coastal areas.

Sonar and other acoustic disturbances:
Since many dolphins and whales rely on sound for navigation, underwater acoustic disturbances from oil exploration, military sonar or other sources may cause disorientation that could result in a stranding.


7 Jenis Ikan Tuna di dunia

Ikan tuna adalah jenis ikan yang memiliki bentuk sperti torpedo termasuk ikan pelagis yang dapat berenang sangat cepat, kecepatan ikan ini dapat mencapai 77km/jam. Ikan tuna merupakan hewan yang memiliki nilai jual tinggi di pasaran.
Jenis ikan tuna yang biasa di tangkap antara lain adalah :
1. Thunnus alalunga , albakora


Thunnus alalunga adalah jenis ikan tuna yang memiliki nama lain sirip panjang, tuna sirip panjang, tuna albakora, albakor, tuna jabrig, madidiang albakoro, tombo ahi, binnaga, albakora pasifik, bonito jerman, suree, aji-aji, trakulu, kwandang, cucut jenggot, albi,
2. Thunnus albacares
Jenis ikan tuna yang mengembara di lautan tropika dan ugahari di seluruh dunia memiliki nama lain tuna madidihang, tuna sirip kuning atau tuna jabrig
3. Thunnus atlanticus , tuna sirip hitam.
Jenis ikan tuna yang memiliki punggung berwarna hitam ikan ini biasa disebut tuna sirip hitam
4. Thunnus maccoyii, tuna sirip biru selatan.
Jenis ikan tuna yang memiliki sirip biru di temukan di perairan selatan samudra dunia nama lainnya tuna sirip biru selatan
5. Thunnus obesus, tuna mata besar.
Ikan tuna thunnus obesus memiliki nama lain tuna mata besar, tuna mata belo, sisiak bonta, bungkulis, ikan tuna ini biasa ditemukan diperairan terbuka samudra tropis dan iklim sedang
6. Thunnus orientalis , tuna sirip biru Pasifik.
Ikan tuna thunnus orientalis memiliki nama tuna sirip biru pasifik ikan ini dapat mencapai ukuran 3 meter.
7. Thunnus thynnus, tuna sirip biru Atlantik.
Ikan Tuna thunnus thynnus merupakan ikan tuna yang hidup di samudra atlantik ikan ini memiliki nama tuna sirip biru atlantik berat ikan tuna ini dapat mencapai 450 kg.

10 Jenis Ikan Paling Bergizi di Planet Ini

REPUBLIKA.CO.ID, Ikan dapat membantu seseorang menangkal kanker prostat, depresi, dan masalah penglihatan. Tapi Anda bingung memilih seafood terbaik? Berikut 10 jenis ikan paling bergizi yang ada di Bumi, dilansir dari Rodale News, Jumat (29/5). Ikan-ikan ini bebas dari merkuri dan dioksin, serta mengandung asam lemak omega-3 yang sehat.

Tuna albacore
Anda tak akan mudah mendapatkan ikan tuna albacore di toko-toko dan pasar. Anda bisa membeli tuna-tuna segar yang sudah disertifikasi oleh Marine Stewardship Council secara online. Anda perlu bersyukur karena Indonesia adalah produsen tuna keempat terbesar di dunia.

Salmon yang langsung ditangkap dari alam mengandung asam lemak omega-3 dan menyehatkan otak.

Moluska yang satu ini mengandung seng tinggi yang bisa meningkatkan kesehatan seksual pria. Jika Anda berencana menyantap tiram, maka Anda perlu memastikan tiram yang dijual masih hidup. Cara terbaik menyimpan tiram adalah ke dalam goni atau tas kertas, bukan plastik.

Sarden pasifik
Sarden setara dengan daging kalengan dalam hal prestise gastronomi.

Trout pelangi
Ini adalah ikan lezat yang mempunyai banyak varietas. Ketika Anda memasak ikan ini, biarkan sisiknya. Jika Anda mau resep sederhana, cukup panggang dengan lemon , paprika, atau sedikit saus.

Kerang lebih mudah ditemukan dibanding tuna. Kerang kaya akan zat besi dan seng, seperti tiram. Siapkan kerang dengan sajian tradisional supaya kandungan gizinya tak berkurang.

Char arktik
Char arktik tidak secara luas dikenal karena tertutup kepopuleran trout dan salmon. Namun, ikan ini populer di kalangan koki restoran. Ikan asli perairan Arktik ini ada di sekitar Kanada, Islandia, dan Norwegia.

Ini adalah ikan berdaging putih yang hidup di sungai-sungai air tawar.

Kepiting dungeness
Kepiting dungeness berasa dari Oregon. Kepiting ini jelas berbeda dari kepiting-kepiting lainnya.

Longfin squid
Orang-orang Jepang menjadikannya bahan sushi. Ini adalah sejenis cumi yang benar-benar sehat sebab mengandung omega-3, vitamin B12, dan nutrisi lain yang membantu menangkal depresi.



Manfaat Makan Ikan: Jantung Sehat dan Sperma Kuat

Jakarta, CNN Indonesia — Anda tahu ikan merupakan sumber protein tanpa lemak dan bernutrisi. Namun, penelitian terbaru menemukan alasan lebih menakjubkan lain tentang ikan.

Ikan adalah makanan yang rendah kalori, berprotein tinggi yang baik untuk otak. Semua manfaat tersebut berasal dari asam omega 3 lemak tak jenuh ganda, populer disebut sebagai omega 3, yang banyak terdapat dalam minyak ikan.

Tubuh manusia tidak bisa secara alami menghasilkan omega 3. Meski demikian nutrisi tersebut dibutuhkan oleh tubuh agar sehat.

Hubungan antara omega 3 dan kesehatan jantung sudah sejak lama kita tahu. Namun, beberapa penelitian baru menunjukkan cukup bukti, bahwa ikan yang tinggi asam lemak sangat penting untuk kesehatan tubuh secara umum.

Kabar baiknya, jika Anda bukan penggemar ikan, penelitian mengatakan, makan ikan hanya dua atau tiga kali dalam satu minggu cukup untuk dapat menuai keuntungannya. Salmon, salah satu ikan pendonor omega 3 tertinggi, dengan berat empat ons mengandung sekitar 1,5 gram asam lemak.

Ikan lainnya seperti tuna, sarden, dan halibut juga mengandung kadar omega 3 yang tinggi. Jika Anda seorang vegetarian yang tidak makan produk hewani, Anda bisa mendapatkan jumlah harian asam lemak omega 3 yang disarankan melalui omega-3 DHA atau suplemen minyak ikan.

Meski demikian, dokter tetap menyarankan untuk mendapatkan manfaat sehat ikan dengan mengonsumsi makanan yang nyata. Berikut ini adalah tujuh alasan kenapa Anda sebaiknya menambah dosis ikan pada menu makan Anda, seperti dilansir dari laman Natural Health:

1. Mencegah penyakit jantung

Penelitian di Denmark terhadap 49 ribu perempuan menemukan, perempuan yang mengonsumsi sedikit sampai tidak makan ikan sama sekali memiliki risiko masalah jantung sampai 50 persen. Penelitian itu dimuat dalam jurnal Hypertension: Journal of the American Heart Association. Jumlah tersebut dibandingkan dengan mereka yang mengonsumsi ikan setidaknya satu kali seminggu.

Ditemukan pula, perempuan yang jarang mengonsumsi ikan memiliki risiko penyakit tiga kali lipat lebih tinggi dibandingkan mereka yang sering. Penelitian lain juga menemukan, makan ikan yang tinggi omega 3 dapat memangkas kadar lemak darah, berkontribusi terhadap rendahnya risiko penyakit jantung.

2. Mengurangi risiko Alzheimer

Makan ikan paling sedikit seminggu sekali membantu menjaga neuron materi abu, yakni bagian di otak yang terkait dengan memori dan kognisi. Hal tersebut berdasarkan pertemuan tahunan Radiology Society of North Amerika.

Peneliti menemukan, orang yang mengonsumsi ikan panggang atau kukus, tetapi tidak digoreng, memiliki otak lebih besar dan sel-sel yang yang lebih besar di daerah otak yang bertanggung jawab untuk mengingat dan belajar. Ilmuwan percaya, volume otak yang lebih besar mengecilkan risiko penurunan kognitif dan penyakit Alzheimer.

3. Memperbaiki kesehatan kulit dan rambut

Salah satu kelemahan terbesar diet rendah lemak adalah merampas lemak sehat yang dibutuhkan kulit dan rambut. Membuat kulit dan rambut kusam dan kering. Omega 3 pada ikan adalah jenis lemak sehat sebagai nutrisi untuk menjaga kulit Anda sehat dan rambut berkilau.

4. Menghilangkan depresi

beberapa penelitian menemukan, saat dibandingkan dengan obat antidepresan, omega 3 dalam ikan lebih efektik mengobati depresi dari resep medis antidepresan. Penelitian yang dilakukan terhadap 52 perempuan hamil menemukan, memakan 300 miligram kapsul omega 3 selama hamil secara signifikan mengurangi risiko depresi postpartum pada perempuan.

5. Meningkatkan perkembangan otak

Asam lemak esensial omega 3 yang ditemukan dalam ikan salmon dan ikan yang kaya nutrisi lain adalah nutrisi penting bagi anak-anak. Zat tersebut berkontribusi untuk perkembangan otak. Beberapa penelitian lain bahkan menemukan, mengonsumsi omega 3 dapat menenangkan gejala ADHD.

6. Dosis vitamin D

Ikan air asin merupakan sumber vitamin D. Para ilmuwan mengatakan, vitamin D dapat menangkal penyakit, meningkatkan kesehatan tulang. Tiga ons salmon mengandung 75 persen jumlah harian yang disarankan untuk vitamin D.

7. Sperma kuat

Penelitian terbaru terhadap 188 responden menemukan, mereka yang makan ikan lebih segar, bersama makan sehat lain seperti buah-buahan, sayuran, dan biji-bijjian, memiliki sperma kuat dibandingkan mereka yang tidak melaksanakan diet sehat.




Manta Ray Reproduction

Manta Ray Reproduction

General information about the reproductive habits of manta rays

The reproduction of these fish maintains some similarities with sharks, since they are close relatives. Manta rays are large fish and just like other species they develop within eggs, however, the mother does not release them; it gives birth to live offspring. How can this happen?

We know that animals experiencing birth through which the offspring are born developed are called mammals, and those that lay eggs are oviparous. But there is another name applied to any species that grows in an egg inside the mother’s body and hatches right there, being born alive. In this sense, the manta rays are ovoviviparous animals.

Furthermore, fertilization is internal and involves sexual union of two individuals. This means that the male has to enter one of their copulatory organs called claspers in the female cloaca to transfer its sperm and allow fertilization.

The age at which sexual maturity is reached is not known completely for sure, but it is believed that females take longer to reach sexual maturity than males. In Manta alfredi species, females are mature from 8-10 years of age and males at 6 years of age, approximately, when the width of the disc is about 2.5-3 meters in diameter. Manta birostris females reach maturity also between 8-10 years or to a later age, while members of the opposite sex mature when their disc’s width is 4-4.5 meters. Despite these data, the age when maturity is reached varies from region to region.

Fertility is very low in comparison with other fish because females usually have 1 or 2 offspring maximum at a time. Manta rays deliver once about every 2-5 years and can have offspring for about 30 years. Of course, half of births occur during the first 24 or 25 years.

Courtship and mating

The mating seasons are different. Apparently, in Japan, the giant manta ray mates during the summer and in the Maldives greater reproductive activity was observed during October, November, March and April.

Of course, mating takes place in warm waters and often around the cleaning stations. When males are in heat, they tend to “casually” wander in the stations in search of a receptive female; the latter is likely to release sex hormones in the water to communicate its willingness to mating.

The courtship process may take several days and perhaps even weeks. What happens during this time is very interesting: usually several males congregate around a receptive female and compete to mate with her. This creates what is known as “train mating” characterized by about 25-30 males, arranged one behind the other, following the female’s movements while she leads them all.

At the end of this test, the female chooses a male and it bites its partner’s left pectoral fin to hold her. Then it positions itself so that bellies of both are bonded, and inserts one of its claspers in the female cloaca. The coupling lasts several seconds and usually the female stands still. After mating the male goes away and never returns to take part in parental care.


After fertilization the offspring develop in eggs inside the womb. Inside the egg, embryos are fed by the yolk.

The female hoses the eggs for approximately 1 year (12 to 13 months) until hatching occurs. Then, the young are born alive and independent from the first moment they leave the mother’s body. Delivery usually occurs at night and in shallow water.
Paternal care

“Small” manta rays can measure more than 1 meter in diameter, and since they have few natural predators, they don’t need parental care as such. During the first year of life, babies tend to double in size.

It is believed that these animals have a long life expectancy and longevity is estimated to be at least 40 years.