The mated pairs are youngsters that have just recently hit sexual maturity, so they haven’t had a lot of experience courting and breeding by any means. It’s not at all uncommon for a new, inexperienced pair to spill some eggs like that when mating, sir. The mating embrace is actually quite fleeting. As discussed below, it takes only a few seconds for a female to deposit hundreds of eggs in her mate’s brood pouch, so it’s certainly possible that your male received some are most of the eggs during the exchange even though 20-30 of them may have been spilled.
This is how the copulatory rise — the actual mating that is the culmination of the elaborate courtship ritual — normally takes place.. It is the climax of the entire affair during which the partners meet in midwater for the transfer of the eggs (Vincent, 1990). The female initiates the rise by pushing up from the bottom in mid-Point and the male immediately follows her lead. They ascend through the water column facing each other, with their heads raised high and their abdomens thrust forward (Vincent, 1990). At this point, the female’s genital papillae or oviduct will be everted and protrude slightly from her vent, and the male’s brood pouch is usually fully inflated (Vincent, 1990). As they ascend, the female often continues to Point and the male may continue to Pump (Vincent, 1990). They will meet at the apex of their rise for the nuptial embrace.
The actual transfer of eggs takes place while the couple is suspended in midwater or slowly descending toward the bottom — a maneuver that is every bit as tricky as it sounds. Coitus is marked by an extremely awkward, fleeting embrace, aptly described as little more than a brief belly-to-belly bumping (Vincent, 1990).
As you can imagine, many difficult and delicate maneuvers are required to bring the pair into proper position for this most improbable merging, and inexperienced pairs often struggle to get it right. The female will attempt to insert her oviduct into the gaping aperture of the male’s inflated brood pouch. An inexperienced pair will often end up misaligned, perhaps at right angles to one another or with one of the partners too high or too low to join. This is very typical of the many false starts and abortive attempts that are ordinarily involved. The frustrated couple will separate to rest on the bottom prior to successive attempts. They may require many such rises before the proper positioning is achieved and the crucial connection is finally made.
The female will eventually succeed, with the full and active cooperation of her mate. He positions himself slightly below his mate, with the aperture of his pouch fully dilated and gaping open, ready to receive her eggs. The female will hover directly over the aperture until she can actually insert her oviduct into the opening at the top of his brood pouch or drop her eggs into the basket while hovering directly above the pouch. Pairs occasionally entwine tails when joined, but more often than not their tails will be stretched back behind them, out of the way.
If she makes a good connection, she will extrude her eggs in one long, sticky string, and the pair will hang together in midwater while the transfer is completed, drifting slowly downward as the eggs surge downward deep inside the pouch (Vincent, 1990). The entire clutch — up to 1600 eggs — is transferred in one brief embrace lasting a mere 5-10 seconds (Vincent, 1990). Sperm stream from the male’s urogenital pore into the pouch opening as the eggs are deposited (Vincent, 1990). The couple separates as they descend, drifting slowly toward the substrate. Exhausted by their efforts, the pair seek out comfortable hitching posts for a well-deserved rest. One almost expects to see them light up cigarettes at this point.
The pregnancy-sustaining changes in the male’s pouch begin the moment the last egg is tucked safely away inside this protective pocket. The male’s pouch deflates, compressing the eggs against the pouch lining in order to facilitate implantation. The male then perches and attempts to settle the eggs properly in his pouch, often undergoing a series of agitated contortions, swaying, twitching, or wagging his tail from side to side, and perhaps stretching as though trying to rearrange the eggs more comfortably (Vincent, 1990). He is dispersing the eggs uniformly throughout his pouch, giving each one the best chance to be fertilized and implant in the septum or wall of the marsupium.
Meanwhile, the female’s belly slims down noticeably as she transfers her eggs. She may lose up to 30% of her body weight after depositing a large clutch of eggs (Vincent, 1990). As a result, her abdominal plates or belly rings will be concave or pinched in for the next couple of days.
Eighteen inches of vertical swimming space should be more than adequate for Mustangs to mate successfully and carry out the transfer of eggs. More than likely your young couple just needs a little more practice to become proficient at the awkward maneuvers copulation requires in seahorses. Just make sure that there isn’t too much midwater turbulence, which would make things more difficult, and everything should be fine. Inexperienced as they may be, there is a good chance at least some of the eggs may have found their way into your male’s pouch.
Best of luck with your seahorses, sir! Here’s hoping they prove to be a prolific pair that provides you with plenty of healthy offspring.